class X science

TRANSPORT OF FOOD MINERALS IN PLANTS

A) Name the following :

a) The membrane which allows the solvent to pass through it but not the solute.

b) The process by which solid, liquid and gases move from a place of higher concentration to a place of lower concentration.

c) The upward movement of water and minerals from roots towards the top of the plant.

d) The pull which helps in have conduction of water in case of tall trees.

e) The tissue which helps in conduction of water minerals in the plant.

f) An apparatus used to measure the rate of transpiration.

g) An antitranspirant.

h) A plant having hydathodes.

i) The tissue which helps in conduction of food in plants.

j) Name the disease caused due to deficiency of nitrogen nutrients in plants.

B) Choose the odd one from each of the following giving reason:

a) Osmosis, Diffusion, Active transport, Transpiration pull.

b) Meristematic zone, Shoot cap, Elongation zone, Maturation zone.

c) Conduction, Rranslocation, Transpiration , Ascent of sap.

d) Root pressure, Transpiration pull, Turgor pressure, Capillary force.

e) Egg-membrane, Parchment paper, Goat's bladder, Litmus Paper.

f) Cooling effect, Ascent of sap, Conduction of minerals,  Evaporation.

g) Stomata, Xylem , Lenticel, Hydathodes.

h) Sunlight, Temperature, Humidity , Hydathodes.

i) Tracheids, Teaches, Xylem parenchyma, Sieve plates.

j) Nitrogen , Phosphorus, Potassium , Cooper 

C) Fill in the blanks:

a) ____ tissue is involved in the transportation of water in plants.

b) The young growing tip of the root is protected by ____.

c) ____ occurs through a semi permeable membrane.

d) ____ is the major component of protoplasm present in a living cell.

e)A plant cell becomes ____ on absorbing water from the soil.

f) Root hairs absorb____ from the soil by active transport.

g) Upward movement of water takes place through _____.

h) ______system of plants absorb water and minerals from the soil.

i) _____ is the inflow of water molecules form an external solution into a cell.

j) A plasmolysed protoplasm swells photo when it is placed in ____ water.

k) Cactus does not have _____ transpiration.

l) Sunken stomata ____  the rate of transpiration.

D) Write true or false and correct the incorrect statements:

a) Osmosis plays an important role in the absorption of water by plants.

b) A semipermeable membrane allows the passage to only solvent molecules through it.

c) Root hairs do not help in absorption of water and minerals.

d) Water is responsible for developing turgor pressure in the cell.

e) Movement of molecules from the region of lower to that of higher concentration is called diffusion. 

E) Choose the correct answer:

1) Ascent of sap occurs due to:

a) root pressure b) transpiration pull c) capillary force  d) all of these 

2) Movement of molecules from a region of higher concentration to the lower concentration through a membrane.

a) diffusion b) active c) osmosis d) all of these 

3) The pressure developed in the root due to continuous inflow water in it

a) Turgor pressure b) root pressure  c) transpiration pull d) none 

4) The upward movement of cell sap in the plants is called :

a) conduction b) absorption c) transpiration  d) none 

5) The tissue which helps in conduction of water and minerals in the plant:

a) Phloem b) Xylem c) vein d) none 

 

ENDOCRINE SYSTEM 

 

A) Name the following:

a) Ductless glands which release their secretion into bloodstream .

b) which gland is called master gland ?

c) which gland is called emergency gland .

d) name the disease caused due to the dietary deficiency of iodine 

e) Name a gland having dual function 

B) Fill in the blanks :

a) deficiency of___ cause diabetes.

b) ____ is called stress hormone.

c)  Testes secrete____ in males.

d) _____ is called master gland.

e) _____ regulate the calcium and phosphorus in the ratio body.

C) Write true or false statement and correct the incorrect statements 

a) thyroxine hormone causes critination in early growing age.

b) pancreas releases emergency hormone, i.e, Adeline hormone

c) parathyroid glands regulate calcium and phosphorus balance in the body.

d) glucagon lowers blood sugar level.

D) Give one word for the following :

a) Flight or fight hormone.

b) chemical messenger in our body.

c) glands with duct

d) glands without duct.

e) it lowers the level of glucose in the blood

f) it raises the level of glucose in the blood.

CURRENT ELECTRICITY 

1) A conductor of resistance 4 Ω can pass a current up 2.5 A through it. Calculate the potential difference required across the conductor.        10V

2) Calculate the amount of work done in moving a charge of 5 C through a potential difference of 25V. What will be the potential difference if this amount of work is done in moving a charge of 10C ?       12.5V

3) A metallic wire of length 1m is stretched to double its length in such a way that there is no change in density of the wire . Calculate the ratio of the final resistance.     1:4

4) A wire of length 15m and uniform cross section of 6x 10⁻⁷m² has a resistance of 5Ω. Calculate the resistivity of the material of the wire.    2 x 10⁻⁷Ωm

5) When a potential difference of 4V is applied across the ends of a wire of 10m length, a current of 2A flows through it. Calculate 

a) the resistance per unit length of the wire.     0.2Ω m⁻¹

b) the resistance of 4m length of this wire.      0.8Ω

6) A battery supplies a current of 0.8 A through a 2Ω resistor and a current of 0.4A through a 5Ω resistor. Calculate the internal resistance of the battery.     1Ω

7) What will be the equivalent resistance of three resistors of 4Ω, 8Ω and 16 Ω if these are connected in 

a) series.    28Ω

b) parallel.      2.28Ω

8) A lamp of resistance 800 Ω, a fire alarm of resistance 30 Ω and a vacuum cleaner of resistance 200Ω are connected in parallel to the mains supply of 240 V. Calculate the current through each appliance and the total current supplied by the mains.    9.5A

9) The effective resistance of two resistors is 25Ω. If the resistance of one of the resistors is 10 Ω, what is the resistance of the other resistors ?     15Ω

10) The effecttive resistance of three resistors connected to a battery is 5 Ω. If R₁ = 10Ω, R₂ = 15Ω, what will be the value of R₃ ? Draw a circuit diagram with the flow of current across each resistor.      30Ω

11) A parallel pair of resistors of values 4Ω and 12 Ω are together connected in series with another resistors of value 3 Ω and battery of emf 24 V. Draw a circuit diagram and calculate the current across each resistor .        3A, 1A

12) The figure below shows

V-I graphs of two metallic conductors for series and parallel combination. Which graph represents parallel combination ?

13) The lengths of three conducting wires of same materials are in the ratio 1:2:3. The area of cross section of each wire is same, if these wires are joined in parallel across a battery, what will be the ratio of the currents in them ?     6:3:2

14) In the given circuit diagram,

the emf of the cell is 5 V and its an internal resistance is 2.5 Ω. Calculate the current flowing in the circuit.    0.67A

15) Find the current flowing through the given circuit connected to a cell of supply 5V. 

  3.75A

16) From the circuit flow diagram given below,

Calculate the current flowing through the circuit.      0.67A

17) Three resistors of 8Ω, 4 Ω and 2 Ω are connected together in such a way that the total resistance is greater than 8Ω but less than 10 Ω. Suggest a suitable arrangement of how these resistors can be possibly combined and calculate the total resistance.    9.33Ω

18) In the given diagram,

A₁, A₂ and A₃ are three ammeters of negligible resistance. The reading of ammeter A₃ is 1A. Calculate 

a) the readings of ammeter A₁ and A₂.    3A

b) the total resistance of the circuit.     2Ω

19) The diagram below

shows three resistors of 5Ω, 8Ω and 10Ω connected to a battery of emf 10V. Calculate 

a) the potential difference across the parallel resistors 8Ω and 10Ω.   4.7V

b) the current through 8Ω resistors.   0.59A

20) A cell of emf 2.5 V and internal resistance 1.5 Ω is connected to resistors of 5 Ω and 15Ω in series. Draw a circuit diagram and calculate 

a) the current in the circuit.   0.116A

b) the potential difference across each resistor.    1.74V

c) the total potential difference across the cell.     2.32V

21) An electric motor draws a current of 5 A from a 220V line. Determine the power of the motor and the energy consumed in 2 hour.   7.92 x 10⁶J

22) A heater has a power of 1.1 kW at 220V.

a) Find the resistance of the heater.   44Ω

b) Calculate the energy in kWh consumed in a week if the heater is used daily for 4h.    30.8 kWh

23) An electric heater draws 5A of current for 10 minute when connected to 230V power supply. Find the heat energy developed.      690 kJ

24) Find the current flowing through an electric bulb rated as 100W, 220V when connected to a 110 V supply. What will be the power consumed now?    25W

25) Three bulbs, A, B and C, are connected in parallel across 110V source . The rating of bulb is 5oW, 110V,  bulb B is 20W,110 V and bulb C is 100 W, 110V

a) Calculate the current flowing in each bulb.  0.45A, 0.18A, 0.9A

b) Which bulb will glow the brightest ?    C

26) Two resistors with resistance R₁ = 5Ω and R₂=7Ω are connected in series across a battery of emf of 16V. Draw a circuit diagram and find

a) the electrical energy consumed by each resistor in 30 second.265.33J, 371.47 J

b) total power developed in the circuit.      21.28 W

27) In the previous example, if the resistors are connected in parallel instead of series, what would be the electrical energy consumed by each resistor. Draw a circuit diagram for the same.    1536 J, 1097.14 J

28) two bulbs are rated as 40W, 220 V and 40W, 110 V,  respectively. Compare the resistance of two bulbs.    4:1

29) A geyser is rated 1.5kW, 250V. It is connected to 250V mains. Calculate 

a) the current drawn by the geyser.     6A

b) electrical energy consumed in 10h in joules.     54 x 10⁶ J

c) cost of energy consumed at Rs3.50 per kWh.      Rs52.50

30)  Four tube lights of 40 W each, two fans of 100W each and three bulbs of 60W each operate on an average of 8h per day. If the cost of energy is Rs2.50 per kWh, calculate the monthly bill.      Rs324

PERIODIC PROPERTIES AND VARIATIONS OF PROPERTIES (PHYSICAL AND CHEMICAL)

BOOSTER

* In every chemistry classroom and laboratory, you will see Periodic Table of the elements on the wall, because in learning chemistry and in solving chemistry problems, no other source of information is used as often. In its symbols and numbers, and most of all in its structure, the Periodic Table contains information about the chemical behaviour of the elements and about the masses, compositions and structures of their atoms.

* In the beginning of the development of chemistry only a few elements were known. But with the discovery of new elements their number went on increasing gradually and it became inconvenient to remember and study the chemistry of so many elements. This condition led to the necessity of classification of elements so as to facilitate the study of chemistry. The arrangement of the elements according to their similarities and dissimilarities resulted in the formation of Periodic Table . The periodic arrangement of known elements according to their properties in a tabular form is known as Periodic Table.

* The Modern Periodic Law states that the physical and chemical properties of elements are periodic functions of their atomic numbers.

*  In the Modern Periodic Table , there are 7 Periods and 18 Groups .

* Groups I, II, III, IV, V, VI, VII, VIII and 0 (zero) represent various Groups. Groups I to VII are divided in sub-groups A and B.

* Elements of zero Group are called Nobel gases and or inert gases.

* Electron shells increase progressively by one down a Group .

* Elements in the same Group have the same number of electrons in their outermost shells.  As a result, elements in the same Group have similar chemical properties.

*  Elements in the same Period have the same number of electron shells. Electrons in the outermost shell increases progressively by one across a Period.

Periodic properties and their Variations in Periods and Groups 

Atomic size or Atomic Radius: 

Atomic radius is the distance between the centre of the nucleus of an atom and its outermost shell containing the electrons. It is measured in Angstrom, abbreviated as A°. 1 A°= 10⁻¹⁰m. The atomic size of the elements decreases in a Period from left to right. The atomic size of elements increases from top to bottom in a Group .

* Ionization Potential (I. P) or Ionization Energy (I. E):

Ionization potential is the amount of energy required to remove a loosely bound electron from the outermost shell of an isolated gaseous atom. it is measured in electron volt (eV). The energy required to remove the first electron is called first ionization potential. The energy required to remove the second electron is called the second ionization potential. Second ionisation potential is more than the first ionization potential. The ionization potential increases on moving from left to right in a Period. It decreases on moving from top to bottom in a Group .

* Electron affinity(E. A) or Electron Gain Enthalpy: 

Electron affinity is the amount of energy released when an electron is added to the outermost shell of an isolated gaseous neutral atom. It is measured in electron volt (eV). Since energy liberated, we use minus (-1) . For example, the electron affinity of chlorine is -3.82 eV. The electron affinity increases in a Period on moving from left to right. It decreases in a Group when we move from top to bottom .

* Electronegativity (E. N): Electronegativity is the tendency of an atom in a molecule to attract shared pair of electronr towards itself. Electronegativity increases across a Period. It decreases from top to bottom in a Group.

* Metallic Character: It is the property of an atom to lose one or more electrons on heating. It decreases on moving left to right across a Period, and increasees from top to bottom on moving down a Group.

* Non-metallic Character:  It is the property of an atom to gain one or more electrons in order to attain octate in their outermost shell, when supplied with energy. Non-metallic character increases in a Period as we move from left to right, and it decreases in a Group on moving down from top to bottom.

*  Alkali Metals : Alkali metals are those elements which follow immediately after the inert gases in the Periodic Table. They consist of 6 elements, Li( lithium), Na(sodium), K(potassium), Rb(Rubidium), Cs(Cesium) and Fr(Francium).

Physical Properties:

a) Commonly found in a combined state.

b) Soft and can be cut with a knife, except  Li(lithium).

c) Silvery-white and shining metals.

d) Excellent conductors of heat and electricity.

e) Emit electrons under the influence of light.

f) Low melting and boiling points.

g) Low density. ( the density increases on moving down the Group .)

Chemical properties:

a) Highly reactive.

b) React with water to form hydroxides with the liberation of hydrogen and heat.

For example, 2Na+ 2H₂O ---> 2NaOH + H₂ + Heat.

c) React with halogen to form a stable binary compound.

For example, 2Na + Cl₂ ---> 2NaCl.

d) React with hydrogen to form white crystalline compounds.

For example, 2Na + H₂ ---> 2NaH.

e) React with oxygen to form oxides.

For example, 4Na + O₂ ---> 2Na₂O.

f) React with non metals to form electrovalent compounds.

For example, Na+ Cl ---> NaCl.

g) Strong reducing agents.

Halogens:

Elements of Group VIIA are called halogens . They consist of 4 elements. F( fluorine), Cl( chlorine), Br(Bromine) , I(iodine).

Physical Properties:

a) Commonly occurs as salts.

b) Bad conductors of heat and electricity.

c) Atomic size increases on moving down the Group .

d) Electronegativity decreases on moving down the Group .

e) Electron affinity decreases on moving down the Group .

f) Melting and boiling points increases on moving down the Group .

Chemical properties:

a) Reactivity decreases on moving down the Group .

b) React with hydrogen to form covalent hydrides.

 For example, H₂ + I₂ ---> 2HI

c) React with non metals to form covalent compounds.

For example, 2P+ 3Cl₂ ---> 2PCl₃

d) React with metals to form metal halides.

For example, Ca + Cl₂ ---> CaCl₂

e) Strong oxidizing agents. The oxidising property decreases down the Group.

A) FILL IN THE BLANKS :

1) The serial number of an element in the pieriodic Table is also its____. (Atomic number /mass number ).

2) The metallic character_____in a Group as one moves from top to bottom. (Increases/decreases)

3) The metallic character____ in a Period as one moves from left to right. (Increases/decreases).

4) _____is the most active nonmetal.(Chlorine/ Iodine)

5) _____is the most active metal.(Magnesium/ sodium)

6) An increase in nuclear charge____ the tendency of an atom to accept electrons. (Increases/ decreases)

7) The atomic size____as one moves from left to right across a Period.(Increases/ decreases)

8) The element in Group VIIA which is a liquid at room temperature is____. (F/ Cl/ Br)

9) Nuclear charge of an atom is the____(negative/positive) charge on the nucleus of an atom, equivalent to the atomic____(numbers/mass) of an atom.

10) Atomic size of neon is_____than the atomic size of fluorine.(More/ less)

11) With increase in nuclear charge the nuclear attraction for outer electron____(increasees/ decreases), Hence ionisation potential____(increases/ decreases). 

12) If an element has one electron in its outermost shell. Then it is likely to be____. (Non metallic/ metallic)

13) The Properties of elements are periodic functions of their____. (Atomic numbers/ mass numbers

14) The element below sodium in the same Group would be expected to have a___. (Lower / higher) electronegativity than sodium and the element above chlorine would be expected to have a_____(lower / higher) ionisation potential than chlorine.

15) On moving from left to right in a given Period, the number of shells___. (Remains the same/ increases/ decreases)

16) On moving down a Group, the number of valence electrons_____( remains the same/ increase/ decreases)

B) CHOOSE CORRECT OPTION:

1) The chemical properties of an element depends on its:

a) atomic mass

b) atomic number

c) atomic energy

d) atomic volume

2) Total number of vertical columns (Groups) in the Long Form of the Periodic Table is :

a) 8 b) 18 c) 17 d) 16

3) The element having the lowest ionisation potential in period 3 is:

a) Na b) K c) Mg d) A

4) The number of elements present in Period 3 is :

a) 6 b) 32 c) 18 d) 8

5) On going down a Group, the number of valence electrons.

a) increases b) decreases

c) remains the same

d) varies irregularly

6) The number of Periods in the Long Form of Periodic Table is:

a) 6 b) 7 c) 8 d) 10

7) On moving down a Group, the size of atoms :

a) increases b) decreases

c) remains the same

d) varies irregularly

8) Which one of the following ions has the smallest radius ?

a) Cl⁻ b) K⁺ c) S²⁻ d) Ca²⁺

9) On moving from left to right in a Period the metallic character of elements:

a) increases

b) decreases

c) remains the same

d) varies irregularly

10) The correct order of decreasing first ionisation potential is :

a) C > B > Be > Li

b) C > Be > B > Ki

c) B > C > Be > Li

d) Be > Li > B > C

11) Which halogen has the highest electron affinity ?

a) F b) Cl c) Be d) I

12) The most electronegative element in the Period Table is:

a) N b) O c) Cl d) F

13) Which has the smallest size?

a) Na⁺ b) Al³⁺ c) Mg²⁺ d) P⁵⁺

14) Which of the following is the correct order of ionisation potential in the Periodic Table?

a) F > O > N > C

b) O > F > N > C

c) O > N > F > C

d) C > N > O > F

15) The electron affinity for noble gases is likely to be:

a) high b) small c) zero d) Positive

16) Which of the following has the highest electron affinity?

a) F b) O c) O⁻ d) Na⁺

17) The size of a positive ion is:

a) more than its atom.

b) less than its atom

c) equal to its atom

d) none of the above

18) Which one of the following is correct order of the size ?

a) I > I⁻> I⁺ 

b) I > I⁺> I⁻   

c) I⁺ > I⁻> I   

d) I⁻ > I > I⁺ 

19)The size of chloride ion (Cl⁻) is

a) smaller than chlorine atom

b) bigger than chlorine atom

c) equal to that of chlorine atom

d) none of the above

20) The ionic radii of N³⁻ , O²⁻ , F⁻ and Na⁺ follow the order

a) N³⁻ > O²⁻ > F⁻ > Na⁺

b) N³⁻ > Na⁺ > O²⁻ > F⁻  

c) Na⁺> O²⁻ > N³⁻ > F⁻  

d) O²⁻ > F⁻ > Na⁺ > N³⁻

C) NAME THE FOLLOWING:

1) The element present in the first Period.      

2) The biggest atom in the third Period.    

3) A solid halogen.    

4) The smallest element of third Period.   

5) The family of elements to which chlorine belongs.   

6) The family of elements to which sodium belongs.     

7) The family of elements to which argon and neon belongs.    

8) Least electronegative element of halogen family.    

9) A non metal which has three electrons in its outermost shell.  

10) The smallest atom in the third Period.      

11) The least reactive elements in Group IA.   

12) The most metallic element in the third Period.  

13) The most nonmetallic element in the third Period. 

14) The element which is most electronegative in the third Period.   

15) A greenish yellow gas other than chlorine.   

16) The most abundant halide salt.     

17) The element which has the highest ionisation potential.  

18) The element of third Period which has least ionisation potential.    

19) The most electronegative element of second period.    

20) An element in period 3 with electronegativity 3.0.   

21) The element with the least ionisation potential in the 2nd period.     

22) The element which has the highest electron affinity in the third Period.    

23) The noble gas having an electronic configuration 2,8,8.  

24) The valency of elements in Group I.    

25) An element of group VIIA, solid at room temperature.        

D) TRUE/FALSE

1) The electron present in the outermost shell are called valence electrons.   

2) In a group, atomic and ionic radii decrease from top to bottom due to increase in the number of shells.     

3) The electron affinity of elements increases in a group from top to bottom and decreases along a Period from left to right.      

4) The amount of energy required to remove a loosely bound electron from the outermost shell of an isolated atom is called ionisation potential.      

5) Electron affinity is the property of an atom to attract electrons towards itself, when combined to form a compound.    

6) Lithium resembles radium and potassium in electropositive character and univalency.      

7) The element in a Group have consecutive atomic Numbers.      

8) On going down in a Group of the Modern Periodic Table, the metallic character of elements increases.      

9) The tendency of an atom of an element to donate or lose electrons is called electropositivity.           

10) Iron is a non-metal.          

E) DEFINE:

1) Periods in Periodic table

2) Group in Periodic table

3) Periodicity

E) ANSWER THE FOLLOWING:

1) What are Periods ?

2) How many electrones are present in the valency shell of the element with the atomic number 18 ?

3) Explain why electron affinity of an atoms increases from left to right along a Period in the Modern Periodic Table.

3) What happens in the number of valence electrons in the atoms of elements as we go down in a Group of the Modern Periodic Table ?

4) From amongst Be, B, and C, choose the element with the highest ionisation potential.

5) What is similar in the electronic structure of Li, Na, and K ?

6) Which of the following elements are in the same Group of the Periodic table ? Magnesium, Nitrogen, Beryllium, Sulphur 

7) Which group of elements was missing from Mendeleev's original Periodic table ?

8) State the Periodic law on which Mendeleev's Periodic table was based ?

9) In the Long Form of the Periodic Table. the elements are arranged according to their mass numbers. Is this statement correct ? if not, correct it.

10) How could the atomic radius of a noblw gas compered with other elements in a Period ?

11) What similarity do halogen show in their molecular state ?

12) Why is ionization potential of O less that of N ?

13) Explain why the elements with low ionisation potential exhibit metallic properties.

14) Account for the difference in size of Fe²⁺ and Fe³⁺ as Fe²⁺ = 0.76 A° and Fe³⁺ = 0.64 A°.

15) Give the formula of one species positively charged and one negativity charged that will be iso-electronic with Ne.

16) Mg²⁺ ion is smaller than O³ ion  althrough both are iso-electronic. Explain .

17) What is the probable formula of the oxide of silicon ? (Silicon occurs below carbon in the Periodic Table)

18) What would you expect the formula of a compared of hydrogen with an element I to be ? ( use I as the symbol of the element.)

19) How do the nature of oxides of the elements change on moving from top to bottom in a Group of the Periodic Table?

Give example.

20) What is the common feature of the electronic configuration of the elements at the end of Period 2 and Period 3 ?

21) if an element is in group 7(or group 7A). is it likely to be metallic or nonmetallic in character ?

22) What is meant by a group in a Periodic Table ?

23) theelectronegativities of the elements in period 3 of the Periodic Table are as follows with elements arranged in alphabetical order:

Al    Cl     Mg     Na      P      S       Si

1.5  3.0   1.2    0.9     2.1   2.5    1.8 

Arrange the elements in the order in which they occur in the Periodic Table from left to right. ( The group 1 element first, followed by the group 2 element and so on, up to Group 7.)

24) Predict the Group of an element X if its atomic number is 16.

10) Select the correct order of radii of three species Ca, Ca⁺ and Ca²⁺

a) Ca > Ca⁺ > Ca²⁺

b) Ca²⁺ > Ca⁺ > Ca

c) Ca⁺ > Ca > Ca²⁺ 

d) Ca⁺ > Ca²⁺ > Ca

Assign suitable reason.

11) Electron affinities of two elements A and B are as follows:

A=3.79 eV and B= 3.56 eV 

Which of them will ionise more easily and why ?

12) How does the number of valence electrons vary on moving from left to right:

a) in the first Period of the Periodic Table?

b) in the second Period of the Periodic Table?

c) in the second Period of the Periodic Table?

13) The elements lithium, sodium and potassium were put in one Group on the basis of their similar properties.

a) What are those similar properties

b) What is the usual name of this Group or family.?

14) Which is larger, Na⁺ or K⁺ ? Why?

15) Chlorine , bromine and iodine elements were put in one Group on the basis of their similar properties:

a) What are those similar properties ?

b) What is the common name of this Group or family ?

16) In the following set of elements, one element does not belong to the set. Select this element.  Give reason in support of your answer.

Calcium, Magnesium, Sodium, Beryllium .

17) Consider the following elements: Na, Ca, Al, K, Mg, Li

a) Which of these elements belongs to the same Period of the Modern Periodic Table ?

b) Which of these elements belongs to the same Group of the Modern Periodic Table ?

18) What is the cause of periodicity of elements in the Periodic Table?

19) What are the following Groups known as?

a) Group IA

b) Group VIIA

c) Group Zero 

20) How did the following properties vary in a Period, say Period 3 ?

a) Atomic size

b) Metallic character

c) Non-metallic character

d) Ionisation potential 

e) Electron affinity 

f) Electronegativity

21) a) Name the elements of Period 3.

b) Which element in Period three is likely to react most violently with chlorine.

c) Of the 8 elements in Period 3, which is likely to form a compound of the formula XCl₃  with chlorine.

22) Match the following 

Column A 

a) Proton 

b) Sodium 

c) Barium 

d) Chlorine 

e) Electron

f)  Completed shell 

Column B 

i) An alkaline earth metal 

ii) halogen 

iii) noble gas 

iv) An alkaline metal 

v) Responsible for nuclear charge

vi) Occupied subshell 

23) Among the elements of the second Period (Li to Ne), pick out the element.

a) with the largest atomic size.

b) with the highest ionisation potential.

c) with highest electron affinity.

d) With highest electronegativity.

e) which is the most reactive metal.

f) which is the most reactive nonmetal.

24)a) How many Groups and Periods are there in the Modern Periodic Table ?

b) On what basis is an element placed in a particular Period in a Group ?

c) The electronic configuration of three elements A, B and C are as follows:

A-- 2   8    18    18     8    1

B-- 2   8    18    18     7

C-- 2   8    18.   32    18   8

Find the respective Period and Group to which each of them belongs.

25) For each of the following pairs, predict which one has a greater ionization potential and greater electron affinity ?

a) I, I⁻

b) B, C

c) Li, Li⁺

26) What is the number of elements in:

a)  first Period of the Modern Periodic Table ?

b) 2nd Period of the Modern Periodic Table  ?

c) 3rd Period of the Modern Periodic Table?

27) a) What are alkali metals ?

b) In which Group and Sub groups are they are placed ?

c) What is their valency ?

d) Why do they not occur free in nature?

28) This question refery to the elements of the Periodic Table with atomic numbers from 3 to 18. Some of the elements are shown by letters, but the letters are not the usual symbols of the elements.

3    4    5    6    7    8    9    10 

A    B    C   D    E    F    G    H 

11 12  13  14  15  16  17  18 

 I     J     K    L    M   N    O  P 

Which of these elements:

a) are noble gases ?

b) are halogens ?

c) are alkali metals ?

d) are elements with valency 4?

29) An element X belongs to Period 3 and Group II of the Periodic Table . State :

a) the number of valence electrons .

b) valency of the element.

c) is it metal or nonmetal.

d) the name of the element.

 

30) The atoms A and B have electronic configuration (2, 8, 2) and  (2,6) respectivaly.

a) to which Period do A and B belong ?

b) to which group do A and B belong ?

c) What are the valencies of A and B with respect to hydrogen ?

d) What is the formula of the compound of A and B ? Is the compound ionic or covalent in nature ?

31) An element X belongs to Period 2 and another element Y belongs to Group 15 of the Periodic Table.

a) What is the number of valence electrons in X ,?

b) What is Valency of X ?

c) What is the number of valence electrons in Y ?

d) What is the valency of Y?

32) In any vertical column of elements in the sub group A of the Periodic Table , as you go from top to bottom :

a) the elements become ____metallic (less /more)

b) the number of electronic shells ____ (increases/decreases)

c) The ionization potential ______. (decreases/ increases)

d) the electronegativity_______ (decreases/ increases).

33) a) What are noble gases ?

b) What is the speciality of the their outermost shells ?

c) in which group are they placed  ?

d) why is that Group referred to as Zero Group  ?

e) why are they referred to as inert gases ?

34) a) What are halogens ?

b) in which Group and Sub groups are they placed ?

c) What is their valency ?

d) Why are they called halogens ?

e) why do they not occur free nature ?

35) Arrange the elements of Group VIIA according to the given conditions:

a) increasing order of atomic size.

b) Increasing non metallic character.

c) increasing ionization potential.

d) increasing electron affinity.

e) decreasing electronegativity .

36) The electronic configuration of an elements T is 2, 8, 7.

a) What is the Group number of T ?

b) What is the Period number of T ?

c) How many valence electrons are there in an atom of T ?

d) What is the valency of T ?

e) is it a metal or nonmetal ?

37) Arrange the following elements as per the guidelines in brackets.

a) Cl, Mg, Na, P( in increasing order of atomic size)

b) Al, Cl, Na, S ( in increasing order of ionization potential)

c) Ar, He, Ne (in decreasing order of number of electronics shells).

d) C, Li, F, N, (in increasing order of electronegativity)

e) C, F, Li, O, (in increasing order of electron affinity)

38) The table given below shows the mass number and the number of neutrons in 4 elements -- P,Q, R, S

Elements:              P    Q    R     S 

Mass number:     12   20  23   35

No of neutrons:    6    10  12   18

a) Write down the atomic number of S.

b) Write down the electronic configuration of S.

c) To which Group S belongs ?

d) To  which Period S belongs ?

e) What will be the nature (ionic or covalent) of the compound formed by 

i) R and S

ii) P and S

39) The position of three elements X, Y and Z in the Periodic Table is as shown below:

Group 16     Group 17

     ---                   X

     ----                -----

      Y                   Z

a) What will be the valency of Z ?

b) What is the name of the family to which element Z  belongs ?

c) State whether Z is a metal or nonmetal.

d) will Z be larger or smaller than Y ?

e) State whether Z is more or less reactive than X.

40) Fill in the blanks:

a) Group 3A elements have____ electrons in their outermost shells.

b) Nitrogen has ____electrons in its outermost shell.

c) Group zero elements have_____ electrons in their outermost shells except ____.

d) The outermost shell electrons are also known as____ electrons.

e) When an atom of magnesium unites with another to form a compound. ____electrons of magnesium are primarily involved.

41) Question (a) to (e) refer to change in the properties of elements on moving left to right across a Period of the Periodic Table . For each property, choose the letter corresponding to the correct answer from choices (i), (ii), (iii) and (iv).

a) The non metallic character of the element:

i) decreases ii) increases iii) remain the same iv) depends on the Period 

b) The electronegativity :

i) depends on the member of valence electrons.

ii) remains the same

iii) decreases  iv) increases 

c) The ionization potential 

i) goes up and down 

ii) decreases iii) increases iv) remains the same 

d) The atomic size:

i) decreases ii) increases iii) remains the same iv) sometimes increasees and sometimes decreases 

e) The electron affinity of the elements in Group 1 to 7;

i) goes up and then down 

ii) decreases and then increases

iii) increases  iv) decreases 

F) REASON BEHIND:

1) Sodium is referred to as a normal element.

2) Sodium and potassium are placed in Group I.

3) Noble gases have zero electron affinity values. Explain ?

4) Why is larger Na⁺ or K⁺ ? Why ?

5) Why is the electron affinity for F Less than that of Cl?

6) Why electron affinity of halogen is comparatively high. Give reason.

7) Ionisation potential of alkali metals is comparatively low.

8) Electronegativity of chlorine is higher than that of sulphur.  Why ?

9) Sodium and potassium are called alkali metals . Why ?

10) Why is chlorine more reactive than bromin ?

11) Why Potassium is more reactive than sodium.

class viii chemistry or science

STATES OF MATTER - A

1) Match the Column 

COLUMN I

1) Have a different mass and volume but no definite shape.

2) Are not rigid at all, can flow and take up the shape and volume of the container in which they are stored .

3) Are almost incompressible.

4) Have a definite mass but a no definite volume or shape.

5) Have a low density and highly compressible .

6) Have any number of free surfaces .

7) Have one upper surface .

8) Have no surfaces.

9) Are very slightly compressible .

10) Have a definite mass, volume and shape.

COLUMN II 

A) Solids

B) Liquids

C) Gases.

2) The following table represents the main postulate of the kinetic theory of matter. Correlate the postulate of the kinetic theory in column I with the correct interconnecting word in column II.

COLUMN I

1) All matter in any state is composed of

2) The particles are arranged in an way such that they have existing between them .

3) The particle attract each other with a

4) The intermolecular attractive forces , with increasing distance

5) The particle are in continuous motion and possess 

6) The particles interact and also possess 

COLUMN II 

A) Potential energy

B) force 

C) space or gaps

D) particles 

E) kinetic energy 

F) decreases 

3) Name the state of matter whose characteristic correlates on the basis of the Kinetic theory.

1) Kinetic energy of molecules is least .

2) Intermolecular space is maximum.

3) Intermular force of attraction is negligible.

4) Particles closely packed and can vibrate about their mean positions only.

5) Particles show minimum compactness and are free to move in any direction.

6) Kinetic energy of molecules is very large.

7) Particles less compact and molecules free to move within the particular state of matter, without leaving it, hence the particular state can flow and has a definite volume.

8) Intermolecular force of attraction is maximum and intermolecular space is minimum.

4) The diagram given below represents Interconversations of states of matter from

  i) solid to liquid state 

  ii) liquid to gaseous state 

  iii) solid to gaseous state

a) Correlate the terms in column II with their meaning in column I.

COLUMN I 

1) Solid state to liquid state at a particular temperature.

2) Liquid state to solid state at a particular temperature.

3) Liquid state to gaseous state.

4) Gaseous state to liquid state without fall in temperature.

5) Solid state directly to gaseous (vapour state) without changing into liquid state.

COLUMN II 

A) Solidification 

B) Melting 

C) Vaporisation 

D) Sublimation 

E) Condensation 

b) Complete the blanks in the diagram given below with the terms representing interconversion of states of matter i.e., A to E in Column II.

MATTER AND ITS COMPOSITION - B

1) Name the change of state in which naphthalein changes into vapour .

2) Name a common substance which exists in all the three States of matter.

3) Fill in the blanks with the correct word from the words in brackets to complete each sentence.

a) interconversion and matter is ____(affected/not affected) by change in condition such as temperature and pressure.

b) As per kinetic theory of matter in any state is composed of ____(molecules/atoms or ions/molecules, atoms or ions)

c) The interparticle attractive force ____(increases/decreases) with increasing distance between the particles.

d) The particles are in continuous random motion and passes kinetic energy which___( increases/decreases) on application of heat .

e) Force of attraction of particle of matter in gases is ____(large/negligible).

4) Select the correct term from the terms A to F given below, correlating with each statement 1 to 5

1) Process of changes from gaseous state to liquid state without fall in temperature.

2) Process of change from liquid state to solid state at a particular temperature.

3) Temperature at which liquid changes into gaseous state at a pressure of 760 of Hg.

4) Process of change from liquid state to gaseous state.

5) Temperature at which liquid changes into a solid at a pressure of 760 mm.

A) Solidification B) Vaporization  C) Melting point  D) Solidification E) Boiling points  F) Liquification 

5) Select the correct word from the words in a bracket to compete each statement:

a) The quantity of matter represents___ while the gravitational pull its ___(weight/mass)

b) ____(iodine/naphthalene) is an example of a solid which is sublimes in the absence of heat.

c) Solidification is also termed as____ (fusion/ freezing).

d) The kinetic energy of molecules in a solid is____(low/very large).

e) In ammonium chloride the intermolecular force is____(high/ low)

6) Select the term, from the terms 1 to 5 which represent the changes A to E as shown in the diagram.

1) Condensation  2) Melting  3) Solidification 4) Sublimation 5) Vaporization 

7) Fill in the blanks given below with the words 'increases' or 'decreases' in each case:

a) During Solidification or freezing, the intermolecular force of attraction ____.

b) On heating a liquid at its melting point, the intermolecular distance _____ .

c) Ice melts at 0°C. At its melting point, the intermolecular force of attraction ___ .

d) Change from gaseous state to liquid state results due to____  in intermolecular distance.

e) On heating a sublimable solid,  the intermolecular force of attraction____ .

7) Give reasons for the following:

a) Solids ,liquids and gases are considered as a matter , but light is not.

b) On heating a solid at its melting point the intermolecular distance of the particles increases.

c) On heating a liquid at its boiling point, heat energy is converted to potential energy.

d)  Sublimable solids directly changes to gaseous state on heating.

e) At its freezing point a liquid changes into a solid

PHYSICS

1) What do you understand by the term "light energy "?

2) What do you understand by the term rectilinear propagation of light ?

3) Give two everyday phenomena which suggest that light travels in straight lines.

4) What do you understand by the following term? Give three examples In which case.

a) Transparent medium.

b) Translucent medium.

c) Opaque body.

5) Define the following terms regarding reflection of light:

a) Mirror

b) Incident ray.

c) Point of incidence.

d) Reflected ray.

e)  Normal 

f) Angle of incidence.

g) Angle of reflection.

h) Glance angle of incidence.

i) Glance angle of reflection.

5) State two laws of reflection.

6) State 5 characteristics of the image formed in the plane mirror.

7) What do you understand by the term reflection of light?

8) Define by giving an example, drawing a diagram and one use of the following:

a) Regular reflection.

b) Irregular(Diffused) reflection.

9) Define the following terms with reference to reflection of light:

a) Image

b) Real image.

c) Virtual image.

10) Draw a diagram to show reflection of rar of light using a plane mirror. In the diagram label the incident ray, the reflected ray, the normal, the angle of incidence and the angle of reflection.

11) By drawing two ray diagrams,

show how eye sees image.

12) a) Diagram shows two plane mirrors inclined at an angle of 90°.

By drawing two ray diagram, Show how an eye sees the images.

b) Which of the images formed above is brightest and why?

13) An insect is sitting in front of a plane mirror at a distance of 1m from it.

a) Where is the image of the insect form formed?

b) What is the distance between the inset and the image ?

14) Name a mirror which always produces an erect and virtual image of the same size as the object.

15) Distinguish between the real and the virtual image.

16) An object is placed at distance of 2cm from a plane mirror. If the object is moved 1cm towards mirror, what will be new distance between the object and the image?

17) Define the following terms:

a) Concave mirror.

b) Convex mirror.

18) What do you understand by the following terms with respect to a spherical mirror?

i) Pole 

ii) Centre of curvature.

iii) Principal axis.

iv) Principal focus.

v)  Focal length

vi)  Eadius of curvature.

vii) Aperture

19)a) In the diagram,

shown is a concave mirror M. A is a point on the principalnaxis. If an object is kept at A, the image is formed on itself. Draw the image in the diagram.

b) Is this image real or virtual ?

c) Measure the distance PA.

d) What is the distance PA called ?

e) Mark a point B on the principal axis at which. If a point source of light is kept, the ray travel parallel to principal axis after reflection from M. What is the point called ?

20) State the relation between the focal length and the radius of curvature.

21) a) An object O is placed at point A,

in front of a concave mirror. Show by two ray diagram, how the image is formed. 

b) State four characteristics of the image.

22) a) What is a real image ?

b) Is real image always inverted ?

c) What type of mirror is used to obtain a real image ?

d) Does the mirror named by you always form real image for all locations of the object ?

23) An object OA is placed on the principal axis of a concave mirror as shown in diagram.

Complete the diagram to show the formation of the image.

24)a) Name a mirror which always forms virtual, erect image of the same size as the object. 

b) Name a mirror which sometimes forms a real image and sometimes a virtual image for different locations of the object.

c) Name a mirror which always forms a virtual, erect and diminished image.

25) Compare the properties of an image formed in case of a convex mirror and a concave mirror when the object is placed between the pole and the infinity.

26) By drawing two rays, show the formation of an image in the diagram given below,

for the object AB. State the size, position and the nature of the image formed.

27) You are provided with a plane mirror, convex mirror and a concave mirror. How will you distinguish between them without touching the mirrors ?

27) Why do drivers prefer a convex mirror as a rear view mirror ? illustrate your answer with a diagram.

28) Give two uses each of:

a) Plane mirror 

b) Concave mirror 

c) Convex mirror 

59) A ray of light is incident on a plane mirror at an angle of 20°. If the mirror is rotated through an angle of 45°, find 

a) Angle between the incident ray and the reflected ray before turning.

b) Angle between the incident ray and the reflected ray when the mirror is turned .

c) Angle through which the reflected ray turns.

d) What conclusion do you draw between the angle through which the mirror turns to the angle through which the reflected turns?

PHYSICS (W)

TEST PAPER - 3

SECTION - I (40 Marks)

Compulsory: Attempt all questions 

1) 

3)

4) The diagram shows a lens as a combination of a glass block and two prisms .. Answer the following question:

a) Name the lens formed .

b) What are the OX and point F called ?

c) Complete the ray diagram and give the formation image.

d) State the characteristics of the image.

5) An electric iron is marked 200V; 550 W.

a) Calculate the current flowing through it when working.

b) Resistance of filament.

c) Energy consumed in 3 hours of continuous working.

d) Expenditure of energy rated at Rs 2 per unit.

6) What is a transformer.

7) What is the value of 

a) a.c voltage supply for household electricity ?

b) frequency of a.c household supply voltage ?

Section - II (40 Marks)

1)

2) 

8)  Distinguish between a real and virtual image.

9) Two straight wires A and B, carrying strong equal currents in opposite directions , pass through a cardboard as shown in the figure. 

Sketch separately the lines of force produced by each current. Show the direction of magnetic field at X.

What will be the effect on the magnetic field at X, if the current in B is reversed ?

Explain why the lines of force at a distance may differ in shape from those in the immediate vicinity of the conductors.

CURRENT ELECTRICITY 

1) A conductor of resistance 4 Ω can pass a current up 2.5 A through it. Calculate the potential difference required across the conductor.        10V

2) Calculate the amount of work done in moving a charge of 5 C through a potential difference of 25V. What will be the potential difference if this amount of work is done in moving a charge of 10C ?       12.5V

3) A metallic wire of length 1m is stretched to double its length in such a way that there is no change in density of the wire . Calculate the ratio of the final resistance.     1:4

4) A wire of length 15m and uniform cross section of 6x 10⁻⁷m² has a resistance of 5Ω. Calculate the resistivity of the material of the wire.    2 x 10⁻⁷Ωm

5) When a potential difference of 4V is applied across the ends of a wire of 10m length, a current of 2A flows through it. Calculate 

a) the resistance per unit length of the wire.     0.2Ω m⁻¹

b) the resistance of 4m length of this wire.      0.8Ω

6) A battery supplies a current of 0.8 A through a 2Ω resistor and a current of 0.4A through a 5Ω resistor. Calculate the internal resistance of the battery.     1Ω

7) What will be the equivalent resistance of three resistors of 4Ω, 8Ω and 16 Ω if these are connected in 

a) series.    28Ω

b) parallel.      2.28Ω

8) A lamp of resistance 800 Ω, a fire alarm of resistance 30 Ω and a vacuum cleaner of resistance 200Ω are connected in parallel to the mains supply of 240 V. Calculate the current through each appliance and the total current supplied by the mains.    9.5A

9) The effective resistance of two resistors is 25Ω. If the resistance of one of the resistors is 10 Ω, what is the resistance of the other resistors ?     15Ω

10) The effecttive resistance of three resistors connected to a battery is 5 Ω. If R₁ = 10Ω, R₂ = 15Ω, what will be the value of R₃ ? Draw a circuit diagram with the flow of current across each resistor.      30Ω

11) A parallel pair of resistors of values 4Ω and 12 Ω are together connected in series with another resistors of value 3 Ω and battery of emf 24 V. Draw a circuit diagram and calculate the current across each resistor .        3A, 1A

12) The figure below shows

V-I graphs of two metallic conductors for series and parallel combination. Which graph represents parallel combination ?

13) The lengths of three conducting wires of same materials are in the ratio 1:2:3. The area of cross section of each wire is same, if these wires are joined in parallel across a battery, what will be the ratio of the currents in them ?     6:3:2

14) In the given circuit diagram,

the emf of the cell is 5 V and its an internal resistance is 2.5 Ω. Calculate the current flowing in the circuit.    0.67A

15) Find the current flowing through the given circuit connected to a cell of supply 5V. 

  3.75A

16) From the circuit flow diagram given below,

Calculate the current flowing through the circuit.      0.67A

17) Three resistors of 8Ω, 4 Ω and 2 Ω are connected together in such a way that the total resistance is greater than 8Ω but less than 10 Ω. Suggest a suitable arrangement of how these resistors can be possibly combined and calculate the total resistance.    9.33Ω

18) In the given diagram,

A₁, A₂ and A₃ are three ammeters of negligible resistance. The reading of ammeter A₃ is 1A. Calculate 

a) the readings of ammeter A₁ and A₂.    3A

b) the total resistance of the circuit.     2Ω

19) The diagram below

shows three resistors of 5Ω, 8Ω and 10Ω connected to a battery of emf 10V. Calculate 

a) the potential difference across the parallel resistors 8Ω and 10Ω.   4.7V

b) the current through 8Ω resistors.   0.59A

20) A cell of emf 2.5 V and internal resistance 1.5 Ω is connected to resistors of 5 Ω and 15Ω in series. Draw a circuit diagram and calculate 

a) the current in the circuit.   0.116A

b) the potential difference across each resistor.    1.74V

c) the total potential difference across the cell.     2.32V

21) An electric motor draws a current of 5 A from a 220V line. Determine the power of the motor and the energy consumed in 2 hour.   7.92 x 10⁶J

22) A heater has a power of 1.1 kW at 220V.

a) Find the resistance of the heater.   44Ω

b) Calculate the energy in kWh consumed in a week if the heater is used daily for 4h.    30.8 kWh

23) An electric heater draws 5A of current for 10 minute when connected to 230V power supply. Find the heat energy developed.      690 kJ

24) Find the current flowing through an electric bulb rated as 100W, 220V when connected to a 110 V supply. What will be the power consumed now?    25W

25) Three bulbs, A, B and C, are connected in parallel across 110V source . The rating of bulb is 5oW, 110V,  bulb B is 20W,110 V and bulb C is 100 W, 110V

a) Calculate the current flowing in each bulb.  0.45A, 0.18A, 0.9A

b) Which bulb will glow the brightest ?    C

26) Two resistors with resistance R₁ = 5Ω and R₂=7Ω are connected in series across a battery of emf of 16V. Draw a circuit diagram and find

a) the electrical energy consumed by each resistor in 30 second.265.33J, 371.47 J

b) total power developed in the circuit.      21.28 W

27) In the previous example, if the resistors are connected in parallel instead of series, what would be the electrical energy consumed by each resistor. Draw a circuit diagram for the same.    1536 J, 1097.14 J

28) two bulbs are rated as 40W, 220 V and 40W, 110 V,  respectively. Compare the resistance of two bulbs.    4:1

29) A geyser is rated 1.5kW, 250V. It is connected to 250V mains. Calculate 

a) the current drawn by the geyser.     6A

b) electrical energy consumed in 10h in joules.     54 x 10⁶ J

c) cost of energy consumed at Rs3.50 per kWh.      Rs52.50

30)  Four tube lights of 40 W each, two fans of 100W each and three bulbs of 60W each operate on an average of 8h per day. If the cost of energy is Rs2.50 per kWh, calculate the monthly bill.      Rs324

CLASS- IX

Week -1   

               CHEMISTRY

(Language of Chemistry, Chemical Reaction)

-----------------------------------------------------

Question 1. (Any Three).       1x3= 3

Classify the following reactions

i) Zn(s) + H₂SO₄(aq)-->ZnSO₄+ H₂ (g)

ii) BaCl₂(aq)+ Na₂SO₄(aq) --> BaSO₄(s) + 2NaCl(aq)

iii) 2CO(g) + O₂(g) ---> 2CO₂(g)

Iv) 2KNO₃(s) ---> 2KNO₂(l)+ O₂(g)

Question 2 (Any Three)        2x3 = 6

Define:

i) Chemical double decomposition

ii) Catalyst

iii) Oxidising agent

iv) Inflammable substance 

Question 3.                                    (2)

CuO(s)+ H₂(g)--------Cu(s)+ H₂O(l).

In the above reaction, by giving reasons, explain which substance is:

i) Oxidised

ii) Reduced

iii) Oxidising agent

iv) Reducing agent

OR

Write the formula of the following:

i) Ammonium sulphate

ii) Zinc carbonate

iii) Lead hydroxide

iv) Barium chooride

Question 4.                                 (3x1)

State the valency and formula of the following:

i) Ammonia

ii) calcium

iii) Ferric

Question 5.                            1x3 = 3

Write the formula and then balance the following equations:

i) Ammonium chloride --> Ammonia+ Hydrogen chloride

ii) Red lead oxide --> lead monoxide+ Oxygen

iii) Sodium nitrate --> sodium nitrite+ Oxygen.

Question 6.                                     (1)

XCl₂ is the chloride of metal X. Write down the formula of sulphate and hydroxide.         

Question 7.                                    (2)

What is the difference between Exothermic and Endothermic reaction.    

CLASS- IX

PHYSICS

F. M- 100.     Time: 2 hrs

1) a) State any four difference between distance and displacement.

b) Give an example of the motion of a body moving with a constant speed, but with variable velocity. Draw a diagram to represent such a motion.

c) A car is moving with a velocity of 72 kmph. The brakes are applied to retard at a rate of 2 m/s². What will be the velocity after 5s of applying the brakes ?   (4+3+3)

2) From the velocity-time graph derive the equation of motion, ut + (1/2) at².

b) Following table gives the displacement of a car at different instants of time. Draw the displacement-time sketch and find the average velocity of the car. What will be the displacement of the car at 2.5s and 4.5 s?

Time (s):                 0    1      2    3     4 

displacement(m):  0    5    10  15   20        (5+5)

3) A spacecraft flying in a straight course with a velocity of 75 kmph fires its rocket motors for 6s. At the end of this time its speed is 120 kmph in the same direction. Find 

i) the spacecraft's average acceleration while the motors were firing.

ii) the distance travelled by the space craft in the first 10s after the rocket motors were started, the motors having been in action for only 6.0s.

b) Derive the mathematical form (F= ma) of Newton's second law of motion.  (5+5)

4) a) Use Newton's second law of motion to explain the following:

i) you pull your hands back while catching a fast moving cricket ball.

ii) you prefer to land on sand instead of hard floor while taking a high jump.

b) Obtain the relationship between S. I and C. G. S units of force.

c) A car is moving with a uniform velocity 30m. It is stopped in 2s by applying a force of 1500N through its breaks. Calculate 

a) the changes in momentum of the car.

b) the retardation produced in car

c) the mass of car.      (4+3+3)

5) a) State Newton's law gravitation. Write an expression for the gravitational force of attraction between two bodies of masses x and y separated by a distance r. Write the numerical value of gravitational constant G with its Si unit.

b) Name and state the action and reaction in the following cases:

i) firing a bullet from a gun.

ii) a book lying on a table.

iii) a person walking on the floor.

c) Define the term acceleration due to gravity. Write its SI unit. Write an expression to show is the acceleration due to gravity related to the mass and radius of the earth.   (4+3+3)

6) a) State four differences between mass and weight.

b) A body of mass 10kg is taken from the Earth to the Moon. if the value of 'g' on the earth 9.8 m/s and on the moon is 1.6 m/s find :

i) the weight of the body on the earth.

ii) the mass and weight of the body on the Moon.

c) State 3 differences between thrust and pressure .    (4+3+3)

7) a) Deduce an expression for the pressure at a depth inside a liquid.

b) Explain why a gas bubble released at the bottom of a lake grows in size as it rises to the surface of the lake.

c) Calculate the height of a water column which will exert on its base the same pressure as 70 cm column of mercury. Density of mercury is 13.6 x 10² kg/m³.    (4+3+3)

8) a) State two factors which affect the atmospheric pressure as we go up. Draw an approximate graph to show the variation of atmospheric pressure with attitude.

b) Name and state the law of transmission of pressure in fluids.

c) What do the following indicate in a barometer regarding weather:

i) gradual fall in the Mercury level.

ii) sudden fall in the Mercury level.

iii) gradual rise in the Mercury level.      (4+3+3)

9)a) State four differences between heat and the temperature.

b) What do you mean by anamalous expansion of water ? At what temperature the density of water is maximum ? State its value.

c) Draw a diagram showing the temperature of the various layers of water in an ice covered pond.    (4+3+3)

10)a) When a bar of iron 50.0 cm long at 15°C is heated in a furnace, it becomes 50.4cm. If the coefficient of linear expansion of iron 0.000011°C, find the temperature of the furnace.

b) What do you understand by zero on Kelvin scale? Write its value in 0°C. State one difference and one feature of similarity between the Celsius and Kelvin scales .

c) The body temperature of healthy person 98.6°F.  Calculate the corresponding temperature on the Kelvin scale.     (4+3+3)

CHEMISTRY (Final)

Time: 1 hr 30+ 10 mins reading time:    Marks-80

GROUP -A

1) Name the principle metal, the composition and two uses for the following alloys.

a) magnalium 

b) stainless steel 

c) German silver 

d) bronze 

e) aluminium bronze

f) brass      (3+4+3.5+3.5+3+3)

2) In the equation given below, state which reaction will proceed and which reaction will not proceed. Give a reason for your answer.     (8)

a) Zn+ CuSO₄ ---> ZnSO₄+ Cu.

b) Cu+ FeSO₄ ---> CuSO₄ + Fe.

c) 3Mg+ 2AlCl₃ --> 3MgCl₂ + 2Al.

d) 2Al + 3ZnSO₄ ---> Al₂(SO₄)₃+ 3Zn.

3) State most important uses of the following non metals.    (12)

i) carbon ii) Nitrogen iii) Oxygen iv) silicon  v) Phosphorus  vi) Sulphur 

GROUP B 

4) a) What is petroleum ?    (2)

b) Name four major fractions obtained and one use of each when petroleum is refined ?   (8)

5) a) How is lamp black prepared on a large scale.     (7)

b) State three uses of lamp black .      (3)

6) What do you understand by the following terms.     10)

a) Radioactivity

b) Radioactive substances

c) oxidation 

d) calcilation of ore

e) roasting of ore 

7) a) What is an alloy ? Why are alloys made.    (4)

b) Name two noble metals and give two uses of each metal named by you.   (4)

c) Calculate the amount of Calcium oxide formed from 2g of calcium metal (Ca=40, O= 16).      (2)

THE PERIODIC TABLE 

1) Complete the statements given below pertaining to different Chemists and their contributions towards classification of elements by chosing the correct words from the following list.

(Mendeleeff, Robert Boyle, Early Chemist, New land, Lavoisier, Doberenier, Carl Scheele, Moseley, Humphry Davy)

a) _______attempted to classify elements on basis of their properties, metallic and non metallic nature, valency  etc, but the classification was discarded and atomic weight and not properties were considered for further classification .

b) ______ classified elements into groups of three on observing a relationship between atomic weights of certain elements and their properties. He arranged elements in increasing order of atomic weights in groups of three called triads.

c) ______ are arranged elements in series in ascending order of their atomic weights and suggested a resemblance between the eighth and first element similar to the 8th and first notes on a musical scale.

d) _______ arranged elements in increasing order of their atomic weights and observed that elements with similar properties appear at regular intervals on arrangement. Such properties are called periodic properties and are those which appear at regular intervals in a periodic table. Examples of such properties are valency, electronegativity, metallic and nonmetallic character.

e) _____ stated that atomic number and not atomic weight of an element should be taken into consideration for classification of elements .

f) _______'periodic law states that the physical and chemical properties of elements are periodic functions of their atomic weights.

g) ______arranged elements in increasing order of atomic numbers in seven horizontal rows called and 18 vertical columns called groups.

2) Name or state the following reference to Mendeleef's periodic table:

a) On what basis was the classification of elements made by Mendeleeff.

b) State the terms used for the following pertaining to Mendeleef's periodic table.

    i) The horizontal rows of elements in the periodic table.

   ii) The vertical columns of elements in the periodic table.

   iii) The properties which repeat themselves at regular intervals in the periodic table.

c) State three contributions made by Mendeleef's which significantly helped to form the basis of the modern periodic table.

d) Give reasons why Mendeleeff periodic table was not completely accepted as the Modern periodic table.

3) Naior state the following pertaining to the Modern Periodic Table.

a) The fundamental characteristics of an element which formed the basis of classification of elements in the Modern Periodic Table.

b) The number of horizontal rows - periods in the table.

c) The number of vertical columns - groups in the table.

d) The period which contains only two elements.

e) The period which contains 8 elements each .

f) The period which contains element having stable electronic configuration 2,8,8.

g) The first element of the periodic table,

h) The type of elements present in the zero group of the periodic table.

i) The last element of the third short period.

j) The period which contains the lanthanide series which is situated at the bottom of the periodic table.

k) The group which are further divided into subgroups A and B.

4) Name or state the following pertaining to the elements of the periodic table.

a) The number of electron shell in the elements of periods one, two or three respectively.

b) The electronic configuration of the zero group element of period-1.

c) The number of valence electrons of the element in group IV of period-2 of the periodic table.

d) The valency of the elements of group IA, VIIA and zero group.

e) The group to which the elements carbon (at no. 6), nitrogen (at no, 7) and oxygen (at no 8)  belong.

f) The period to which sulphur (at no 16) and chlorine (at no 17) belong.

g) The electronegative element from the element sodium, magnesium and sulphur.

h) The type of bonding seen in the oxide of the element in period-3, group IIIA.

i) An element in period-3,  group VA whose chloride exists in two different physical states.

j)  The groups of the periodic table which contains the alkali metals , alkaline earth metals and the halogens respectively.

k) The grouping name given to the type of elements present in groups

      i) IB to VIIB and VIII

      ii) IA to VIIA

l) The non metal positioned in group IA.

m)  The series of chemically reactive metals of period -7 placed at the bottom of the periodic table.

n) The least electronegative elements from the elements chlorine, bromine and Iodine in group VIIA.

o) The element in period-2, group IA, which shows similarity with a divalent metal in period-3 group IIA.

p) The non metallic element in period-2 to which is diatomic and unreactive at ordinary temperatures.

5) State whether the following statements of true or false. If false rewrite the correct statement.

a) Element with similar outer electronic configuration are placed in the same period of the periodic table.

b) If properties of one member of a group is known the properties of other members of the group could be correlated due to similarity or gradation in properties of elements in a group.

c) Non metals occupy the upper right hard corner of the periodic table.

d) The two sub groups A and B accommodate elements with similar properties.

e) Properties of elements remain the same on moving from left to right in the modern periodic table,

f)  Electronegativity and nonmetallic character of elements increases across a period from left to right and decreases down a group.

6) Write i) Electronic configuration ii) Group Assigned iii) Metallic/ nonmetallic iv) Electronegative/Electropositive of the following:

Element      Atomic number 

a) Hydrogen.  1

b) Carbon        6

c) Nitrogen     7

d) Oxygen        8

e) Sulphur       16

f) Chlorine      17

g) Lead            82

h) Bismuth      83

i) Polonium     84

j) Astatine       85

CHEMISTRY TERMINOLOGY - CHEMICAL REACTIONS

      THE LANGUAGE OF CHEMISTRY 

1) State the valency and name the ion or radical in each of the following cases given below (The first example is completed for you):

Electrical ent positive ions or radicals 

Symbol/Valency        Name

a) K¹⁺                        Potassium 

b) Na

c) H

d) NH₄

e) Ca

f) Mg

g) Zn

h) Ba

i) Ni

i) Co

j) Al

k) Cr

Variable valencies 

a) Cu¹⁺

b) Cu

c) Hg¹⁺

d) Hg

e) Fe²⁺

f) Fe

g) Mn²⁺

h) Mn

i) Pb²⁺

j) Pb

k) Pt²⁺

l) Pt

Electrovalent negative ion or radicals

Symbol/valency      Name

a) Cl¹⁻                     Chloride 

b) ClO₃

c) ClO

d) Br

e) I

f) OH

g) NO₂

h) NO₃

i) HCO₃

j) HSO₃

k) HSO₄

l) AlO₂

m) MnO₄

n) SO₃

o) SO₄

p) S

q) CO₃

r) O

s) CrO₄

t) Cr₂O₇

u) ZnO₂

v) PbO₂

w) PO₄

x) N

y) C

2) State the valency of each of the elements in the respective compounds:

a) Sulphur in    (i) sulphur dioxide 

                           ii) sulphur trioxide 

b) Nitrogen in    i) Nitrogen monoxide 

                           ii) Nitrogen dioxide 

                          iii) dinitrogen oxide 

                          iv) dinitrogen pentoxide 

c) Copper in      i) cupric oxide 

                          ii) Cuprous oxide 

3) Give the formulas of the following compounds whose metallic radical exhibits variable valency.

a) Cupric nitrate.

b) Cuprous chloride.

c) Iron(II) sulphate.

d) Mercuric nitrate.

e) Plumbous chloride.

f) Stannous chloride.

g) Mangannic sulphate.

h) Platinic chloride.

i) Mercurous chloride.

j) Iron [II] nitrate.

4) Give the name of the compounds whose formulas are listed below:

a) HNO₂       ___

b) HCO₃            |

c) H₂C₂O₄.        |

d) H₃PO₄          |   --- Acids

e) CH₃COOH    |

g) Al(OH)₃

h) CaSiO₃.

i) Na₂ZnO₂.

j) K₂CrO₄.

k) Mg₃N₂.

5) A chemical equation is a shorthand form for a chemical change 

a) 2KClO₃  ---∆--> 2KCl + 3O₂.

     i) In the above reaction name the reactant and the products.

     ii) State what the arrow in between indicates.

6) Balance the following equations.

a) CuO+ NH₃ --> Cu + H₂O + N₂.

b) NH₃ + Cl₂ --> HCl + NCl₃.

c) Mg₃N₂ + H₂O --> Mg(OH)₂ + NH₃.

d) Pb₃O₄ + HCl --> PbCl₂ + H₂O + Cl₂.

e) Manganese [IV] + Hydrochloric acid --> Manganese (II) Chloride+ Water + Chlorine.

f) Potassium hydroxide + Chlorine --> Potassium chloride + Potassium hypochlorite + Water.

g) Ammonium dichromate --> Chromiumoxide + Water+ Nitrogen.

h) Potassium sulphite + Nitric acid --> Potassium nitrate+ Water+ Sulphur dioxide.

i) Iron [II] chloride + Water + Sulphur dioxide --> Iron [II] Chloride+ Sulphuric acid+ Hydrochloric acid.

j) Copper+ Sulphuric acid --> Copper sulphate + Water+ Sulphur dioxide.

k) Iron [III] oxide + Carbon monoxide --> Iron + Carbon dioxide.

l) Sodium sulphite+ Sulphuric acid --> Sodium sulphate+ Water+ Sulphur dioxide.

m) Zinc + Sodium hydroxide --> Sodium zincate --> Hydrogen.

n) Aluminium+ Carbon dioxide --> Aluminium oxide + Carbon.

o) Sodium bicarbonate+ Aluminium sulphate --> Sodium sulphate+ Aluminium hydroxide+ Carbon dioxide.

p) Calcium hydroxide+ Ammonium sulphate --> Calcium sulphate+ Water+ Ammonia.

q) Nitric acid+ Magnesium carbonate --> Magnesium nitrate+ Water+ Carbon dioxide.

r) Iron [III] oxide+ Sulphuric acid --> Iron [III] sulphate+ Water.

s) Zinc sulphide+ Oxygen --> Zinc oxide+ Sulphur dioxide.

t) Carbon+ Nitric acid --> Carbon dioxide+ Water+ Nitrogen dioxide.

7) Match the different types of chemical reactions in column II with the meaning of the type of reactions in column I.

COLUMN I 

a) A chemical reaction in which two or more elements or compounds react to form one new compound as a product.

b) A chemical reaction in which a chemical compound decomposes or splits up into two or more simpler substances. It is generally brought about by heat.

c) A chemical reaction which takes place when an element [or radical] has replaced another element in a compound.

d) A chemical reaction in which two reactants are both the decomposed to form new substances by exchanging their radicals.

e) A chemical reaction which employes a catalyst to alter the rate of a reaction.

f) A chemical reaction in which the products formed react together to form the original reactants depending on the conditions of the reaction.

g) A reaction in which a substance dissociates into two or more simpler substances on application of heat and is a reversible reaction.

h) A reaction which involves addition of oxygen or electronegative element or removal of hydrogen or electropositive element.

i) A reaction which involves addition of hydrogen or electropositive elements or removal of oxygen or electronegative element.

j) A chemical reaction which proceeds with evolution of heat energy.

k) A chemical reaction which proceeds with absorption of heat energy.

l) A chemical reaction which proceeds with absorption of light energy.

COLUMN II 

A) Double decomposition 

B) Exothermic reaction 

C) Reversible reaction

D) Displacement reaction

E) Combination or synthesis 

F) Decomposition reaction

G) Thermal dissociation 

H) Endothermic reaction 

I) Catalytic reaction 

J) Oxidation reaction

K)  Photochemical reaction

L) Reduction reaction.

8) With reference to the reaction -- A to L in column II of the previous question no. 7 state the type of reaction/s to which each of the following belongs :

a) Addition of zinc to copper sulphate solution.

b) Heat on lead nitrate crystals.

c) Preparation of oxygen from potassium chlorate.

d) Conversion of ferrous chloride to ferric chloride using chlorine.

e) Formation of ammonia from nitrogen and hydrogen.

f) Liberation of hydrogen at the cathode acidified water.

g) Manufacture of glucose by green plants.

h) Formation of nitric oxide from Nitrogen and oxygen.

i) Addition of zinc to dilute sulphuric acid.

j) NH₄Cl <=> NH₃ + HCl.

k) 2KNO₃ --∆--> 2KNO₂ + O₂.

l) 2H₂O₂ --H₃PO₄--> 2H₂O + O₂.

m) PbBr₂ --> Pb²⁺ + 2Br¹⁻ [ions].

n) 2HgO --∆--> 2Hg + O₂.

o) N₂O₄ <=∆=> 2NO₂.

p) AgNO₃ + KCl --> AgCl + KNO₃.

q) Fe + S --> FeS.

r) H₂ + Cl₂ --> 2HCl.

                  ˢᵘⁿˡᶦᵍʰᵗ

s) C + H₂O --> CO.

t) Cl₂ + 2KI --> 2KCl + I₂.

u) 3Fe + 4H₂O <==∆=> Fe₃O₄ + 4H₂.

v) 2Cu + O₂ --> 2CuO.

w) Fe₂O₃ + 2Al --> Al₂O₃ + 2Fe.

x) KNO₃ + H₂SO₄ --> HNO₃ + KHSO₄.

y) 2FeCl₂ + Cl₂ --> 2FeCl₃.

z) Fe+ H₂SO₄ --> FeSO₄ + H₂.

a) SO₂ + Cl₂ --> SO₂Cl₂.

b) 3Ca + N₂ --> Ca₃N₂.

c) CuSO₄ + Fe --> FeSO₄ + Cu.

d) 4HNO₃ --> 2H₂O + 4NO₂ + O₂.

8) Oxidation and reduction reactions are generally termed as redox reactions . In the examples given below underline the oxidised product or reduced product in the respective reactions. Underline substance is the oxidising or reducing agent respectively.

Oxidation reactions 

a) Cu + O₂ --> 2CuO.

b) H₂S + Cl₂ --> S + 2HCl.

c) 2FeCl₂ Cl₂ --> 2FeCl₃.

d) SO₂ + H₂O + Cl₂ --> H₂SO₄ + 2HCl.

e) H₂S + 2FeCl₃ ---> 2FeCl₂ + 2HCl + S.

f) Zn + H₂SO₄ --> ZnSO₄ + H₂.

g) Fe + S --> FeS.

h) 2Mg + SO₂ --> MgO + S.

i) 2H₂S + SO₂ --> 3S + 2H₂O.

j) S + 2H₂SO₄ ---> 3SO₂ + 2H₂O.

Reduction reactions 

a) CuO + H₂ --> Cu + H₂O.

b) Br₂ + H₂S --> 2HBr + S.

c) 2FeCl₃ + H₂S --> 2FeCl₂ + 2HCl + S.

d) 2HgCl₂ + SnCl₂ --> Hg₂Cl₂ + SnCl₄.

e) 2FeCl₃ + SO₂ + 3H₂O --> 2FeCl₂ + 2HCl + H₂SO₄.

f) Fe₂(SO₄)₃ + 2H₂O + SO₂ --> 2FeSO₄ + 2H₂SO₄.

g) Cl₂ + 2H₂O + SO₂ --> 2HCl + H₂SO₄.

h) 2HNO₃ + SO₂ --> 2NO₂ + H₂SO₄.

i) 2KMnO₄ + 2H₂O + 5SO₂ --> 2MnSO₄ + K₂SO₄ + 2H₂SO₄.

j) K₂Cr₂O₇ + H₂SO₄ + 3SO₂ --> Cr₂(SO₄)₃+ K₂SO₄ + H₂O.

9) Name the following:

a) A coloured gaseous oxidising agent.

b) A liquid oxidising agent which on thermal decomposition in presence of a catalyst liberates oxygen.

c) A gaseous reducing agent containing Oxygen.

d) An acidic other than nitric and Sulphuric Acid which is an oxidizing agent.

e) A gaseous reducing agent neutral in nature other than carbon monoxide.

f) An oxidizing agent which liberates chlorine on heating with concentric hydrochloric acid.

g) Two neutral gases which react to give a basic gas and the reaction is exothermic.

h) Two neutral gases which react to give a neutral oxide and the reaction is exothermic.

i) A substance which decomposes by absorption of sound energy.

j) Two substances which react explosively on close physical contact.

ATOMIC STRUCTURE 

1) Define the terms 

a) Atomic number 

b) Mass number 

c) Electron

2) From the symbol ⁴₂He for the elements helium, write down the mass number and the atomic number of the element.

3) a) Sulphur as an atomic number of 16 and a mass number of 31. State the number of protons and neutrons present in the nucleus of sulphur.

b) Give a simple diagram to show the electrons in an atom of sulphur.

4) ²⁴₁₂Mg and ²⁶₁₂ Mg are symbols of two isotopes and magnesium. compare the atoms of these isotopes with respect to:

a) the composition of their nuclei.

b) their electronic configurations .

c) give the reason why the two isotopes of magnesium have different mass numbers.

5) Chlorine is an element of atomic number 17. It is a mixture of two Isotopes having mass number of 35 and 37.

a) What is meant by "atomic number of an element"? What do you understand by an 'atom'.

b) Write down the electronic configuration the chlorine atom.

c) State the number of protons , electrons and a neutrons in the following isotopes: ³⁷Cl₁₇, ³⁷Cl₁₇.

d) Explain why the two atoms in (c) above have the same chemical reactions.

e) If molten magnesium chloride is electrolysed suggest suitable electrode(anode).      Carbon 

6) Five atoms are labelled V to Z

Atoms    mass number.  Atomic number 

 V               40                    20

 W              19                     9

 X                 7                     3

 Y               16                     8

 Z               14                     7

i) Which one of these atoms (a) contains 7 protons (b) has an electronic configuration 2.7 ?            Z, W

ii) Write down the formula of the compound formed by atoms X and Y.      X₂Y

7) Element X, Y, Z have atomic numbers 6, 9 and 12 respectively, Which one:

a) forms anions - negative ion.

b) forms cation - positive ion.

c) has 4 electrons in the outermost orbit.

8) The atoms of aluminium is represented by ²⁷Al₁₃. Write down the number of

a( electrons

b) protons

c( neutrons

d) the arrangement of electrons in the different orbits or shells in one atom of aluminium.

9) Name the element which does not contain any neutrons in its nucleus.

10) Elements A, B, C have atomic number 9, 20 and 10 respectively.

a) State which one is (i) a nonmetal (b) a metal  (c) a chemically insert

b) Write down the formula of the compound formed by two of the above elements.

11) Write down the electronic configuration of the following: 

a) ²⁷₁₃X

b) ³⁵₁₇Y.

Write down the number of electrons in X and neutrons in Y and the formula of the compound formed by X and Y.         XY₃

12) Write down:

a) The mass number of the atom having 20 neutrons and 15 protons.

b) The number of neutrons in the nucleus of an atom having atomic number 17 and mass number 37.

13) What is the relation between the number of protons and the number of electrons in an atom.

14) Copy and complete the following table relating to the atomic structure of some elements.

Element    At. No  Mass.no  pro  neu  elect 

Beryllium      4.        9                     

Fluorine        9                                10

Sodium                                           12      11

Phosphate.             31            15 

15) The electronic structure (configuration) of fluorine can be written as 2,7. In a similar way give the electronic configuration of:

a) aluminium

b) phosphorus

16) Represent each of the following:

a) a proton 'p'.

b) an electron 'e'.

c) a neutron  'n' in terms of its symbols showing the subscript and superscript values.

17) An element 'A' has mass number 23 and atomic number 11. State the 

a) number of neutrons in its shell.

b) electronic configuration of the element 'A'.

18) The following elements U and Z are given :

₃U, ₆V, ₉W, ₁₄X, ₁₈Y, ₂₀Z.

State the electronic configuration of each and state whether they are metals, non metals or insert gases.

19) Draw the geometrical atomic structure of each of the following atoms showing the number of electrons, protons and neutrons in each of them:

a) ¹²₆C 

b) ²³₁₁Na

c) ³¹₁₅P

d) ³⁹₁₉K

e) ⁴⁰₂₀Ca

20) Four elements A, B, C, D are given :

A shows the presence of 20 neutrons and 17 electrons.

B shows the presence of 18 neutrons, 17 protons and 17 electrons.

C shows the presence of 10 neutrons, 9 protons and 10 electrons.

D shows the presence of 4 neutrons , 3 protons and 1 electrons.

 State which of the above is-

a) an atom

b) a cation 

c) a pair of isotopes.

 Write the formula of the compound formed between D and C.

21) Difference between the terms -

a) stable and unstable electronic configuration

b) Duplet and octet rule 

c) Electron and proton 

d) atomic number and mass number 

e) nucleus and nucleons 

f) Valence shell and penultimate shell

22) Select the correct answer from the answers in brackets to complete each sentence.

a)  An element has electronic configuration 2, 8, 1 and 12 neutrons. Its mass number is ____( 11/23 /12).

b) The maximum number of electrons in M shell is _____(8/32/18).

c) Isotopes have same____( number of neutrons/ electronic configuration/ atomic masses).

d) An___( atom/ion) is capable of independence existence in solution.

e) An atom with electronic configuration 2,7 and mass number 19 will have____ (8/10/12).

23) Give reasons for the following:

a) the physical properties of isotopes of the same element are not identical.

b) the mass number of an atom is slightly less than the actual atomic mass.

c) the shells surrounding the nucleus of an atom are also called 'energy levels'.

d) Helium is chemically extremely unreactive.

e) Mass number is slightly less than the actual atomic mass.

24) Name the state the following:

a) the three isotopes of hydrogen.

b) Two elements having same number of protons and electrons but different number of neutrons.

c) the valency of an element whose electronic configuration is 2, 8, 3.

d) the shell closest to the nucleus of an atom.

e) An element having valency zero.

25)

State the number of neutrons in each of the atoms A to E. Also state which of the atoms A to E is a metal.

26) Match the elements A to E in list 1 with their valencies in list 2 and with their nature in list 3.

List : 1

A) Atomic number 7, mass number 14

B) Electronic configuration 2,8.

C) neutrons 14, electrons 13

D) neutrons 22, protons 18.

E) electronic configuration 2,8,1

List: 2

1) -3

2) +1

3) +3

4) +2

5) 0

List: 3

X: metal 

Y: nonmetal 

Z: noble gas