a) Water occuring in the combined form in a mineral salt.
b) A naturally occurring gaseous state of water other than water vapour.
c) A liquid free state of occurrence of water above the Earth's surface.
d) A food product containing a large percentage of water in the combined form.
e) An occurrence of water in the free state in the solid from other than ice.
f) Water occurring in the liquid formed in the free state below the Earth's surface.
2) The diagram represents the water cycle. Give reason for the following:
b) Rain water is considered as a very pure form of water compare to river and late water.
3) With reference to the following three properties of compounds, given reasons why water is considered a compound and not an element.
a) Always homogeneous with particles of one kind .
b) Heve a definite set a proporties and component do not retainn their original properties.
c) The components can be separated by chemical means only.
4) Water found in natural state is called "natural water" while that which has received some form of treatment is called"treated water ".
NAME
a) Two sources of natural water other than rain water, river and lake water.
b) The purest form of treated water free from all mineral solutes prepared by condensing steam.
c) A form of treated water prepared by filtration followed by chemical treatment and is generally used for drinking purposes.
d) An acidic gas used for killing germs present in the water in swimming pools.
5) Choose the correct word/s Statement relating to the physical properties of water.
Column I
a) Boiling point of water increases and freezing point decreases.
b) water 4° C has
c) Water has the highest specific heat capacity hence requires
d) Water exhibits anamalous expansion hence on cooling.
e) In terms of conductivity, water is a
Column II
i) With increse in pressure on the surface of water.
ii) with decrease in pressure on the surface of water.
i) minimum density and maximum volume.
ii) maximum density and minimum volume.
i) less heat to raise the temperature by 1°C
ii) more heat to raise its temperature by 1°C.
-- than equal mass of any other substance.
i) first expands but at temperature of 4°C starts contracting.
ii) first contracts but at temperature of 4°C starts expanding.
i) bad conductor of heat but good conductor of electricity.
ii) bad conductor of heat and electricity.
6) Give reason for the following:
a) Water exist in all the three States of matter.
b) Water finds application in modifying the climatic conditions of the land adjacent to large areas of water.
c) Water has the ability to dissolve electrovalent compounds eg., sodium chloride.
e) Marine life exists between frozen Lakes .
f) Benzene does not exhibit anamalous expension but water does.
7) The diagram represents experiments to show the presence of dissolved solids and gases in water. With reference to the experiments answer the following:
a) State the function of the boiling water in 'bekar X'.
b) Give reasons for the following:
i) Concentric rings are seen when the watch glass which initially contained tap water is held towards light.
ii) Similarly concentric rings are not seen when the watch glass which initially contained rain water instead of tap water is held towards light.
c) Write the composition and importance of the dissolve solid in water.
B) Experiment B:
a) Give reasons for the following:
i) The round bottom flask Y is completely filled to the brim with tap water.
ii) The flask is heated till no more bubbles are evolved on boiling.
iii) Dissolved air in water contains a higher percentage of oxygen than ordinary air.
b) Complete the table given below for the composition of dissolved gases in water.
i) Percentage by volume of dissolved gases in
Air %by volume in boiled off % by
air from volume
water
Oxygen
Carbon dioxide
ii) Name the component in boiled off air whose percentage by volume is less than that in ordinary air. State the percentage difference giving reasons.
c) Match the Column
Column I
i) Dissolved oxygen Water used
ii) Photosynthesis in aquatic plants takes place by utilising the
iii) Insoluble limestone layers in water are
iv) Marine animals make or strengthen their shells by
v) In photosynthesis dissolved carbon dioxide is utilised for the formation of carbohydrates and the evolved gas is
Column II
A) carbon dioxide present in dissolved water.
B) oxygen
C) dissolved in the presence of carbon dioxide in water resulting in formation of soluble bicarbonates.
D) respiration by aquatic animals.
E) absorbing the calcium carbonate from the soluble calcium bicarbonate in water.
d) Complete and balance the equation pertaining to the importance of carbon dioxide dissolved in water. [X= carbon dioxide]
photosynthesis
_____ + H₂O ---> + _____H₂O+ ___
ˣ ᵍˡᵘᶜᵒˢᵉ
Formation of shells by marine animals
_____+ H₂O + ____ --> ______
ᶦⁿˢᵒˡᵘᵇˡᵉ ˡᵃʸᵉʳ ˣ ᵃᵇˢᵒʳᵇᵉᵈ ˢᵒˡᵘᵇˡᵉ ˡᵃʸᵉʳ
8) Water reacts with different metals with different reactively depending on their position in the metal activity series .
The above diagrams represents the reactions of potassium, sodium, calcium with cold water. Magnesium , Aluminium , Zinc, Iron also react with boiling water or steam.
From the list of the above metals:
Name the metal which
a) Reacts smoothly cold water and sinks in it.
b) Burns with a coloured flame on reaction with cold water.
c) Forms a residual milky, turbid solution with cold water.
d) Is generally amalgamated and added to cold water for collection of literated hydrogen.
e) Does not react with cold water, but reacts slowly with boiling water.
f) Does not react with cold or boiling water but reacts with steam and is trivalent.
g) Reacts completely very slowly with steam and undergoes a reversible reaction.
h) Reacts with steam forming an amphoteric oxide, yellow when hot-white when cold.
9) Give reason for the following:
a) Synthesis of hydrogen chloride from its elements takes place in the presence of moisture.
b) Sodium is amalgamated (i.e, alloyed with mercury) when used for collection of the liberated hydrogen, on reaction with cold water.
c) Magnesium and aluminium react with steam but the reaction soon comes to a stop. Further heating to high temperatures renders the metal active again, liberating hydrogen.
d) Sodium reacts with cold water, magnesium with boiling water while iron with steam only.
10) Complete and balance the following equations for reactions of different metals(X) with water.
a) ____+ H₂O---> ____+ H₂(X burns with a lilac flame in air)
ˣ ᶜᵒˡᵈ
b) _____+ H₂O---> ___+ H₂(X is divalent and sinks in water)
ˣ ᶜᵒˡᵈ
c) _____+ H₂O ---> _____+ H₂(X is trivalent)
x ˢᵗᵉᵃᵐ ˣ₂ᴼ₃
d) _____+ H₂O ---> ____+ H₂[Y is an amphoteric oxide, yellow when hot)
ˣ ˢᵗᵉᵃᵐ ʸ
e) _____+ H₂O <==> ____+ H₂ (Z is a mixed oxide)
ˣ ˢᵗᵉᵃᵐ ᶻ
11) Name the acid/s formed when the following gases are dissolve in water and give a balanced equation for the same.
a) chlorine
b) Sulphuric dioxide
c) sulphur trioxide
d) carbon dioxide
e) Nitrogen dioxide
12) A given liquid 'X' is to be tested for water.
a) Give two physical tests to prove that the liquid is water.
b) Using
i) copper sulphate
ii) Cobalt chloride.
State the colour change observed when the above anhydrous salts turn hydrous.
13) State the function of water in the following:
a) As a solvent
b) In nature
c) In industry
d) In the human body
13) The diagram below represents the dissolution of sodium chloride in water.
COLUMN I
A) solute 'Y'
B) solvent 'X'
C) solution 'Z'
COLUMN II
i) The substance which dissolves in the solvent to form a solution.
ii) A homogeneous mixture of a solute in a solvent .
iii) The liquid or medium of dissolution which allows the solute to dissolve in it to form a solution.
14) Select the correct statement given below for the properties of a true solution.
COLUMN I
a) A true solution is
b) The particle in a true solution
c) The solute present in the solvent of a true solution can be recovered by
d) a true solution is a
COLUMN II
i) clear and homogeneous in nature
ii) translucent and heterogeneous in nature
i) are molecular, and can be seen under a microscope.
ii) are molecular, cannot be seen under the microscope
iii) pass through the pores of a filter paper, and slowly settle down.
i) chemical and not by physical means.
ii) physical and not by chemical means
i) compound
ii) mixture
15) The diagram below represent preparation of unsaturated and saturated solutions.
Difference between the following:
a) saturated solution/unsaturated solution
b) saturated solution/supersaturated solution
c) Dilute solution/ concentrated solution
d) Dissolution of sodium chloride in water/ slow melting of ice in water
16) Give reasons:
a) A saturated solution can be converted to unsaturated solution by heating the saturated solution very slowly.
b) Conversion of a saturated solution to an unsaturated one can also be brought about by adding more of the solvent to the saturated solution.
c) Cooling a hot saturated solution prepared at high temperatures result in formation of a supersaturated solution.
d) A saturated solution can be distinguished from an unsaturated solution using a small crystal of the solute used in the preparation of the one solutions.
17) Match the appropriate solvents in column I with the solute dissolves in column II
COLUMN I
a) Carbon disulphide
b) oxalic acid
c) Acetone
d) Liquor ammonia
e) petrol
f) Turpentine oil
g) iodine
h) benzene
COLUMN II
i) Grease stains (by emulsifying )
ii) chlorophyll
iii) paint
iv) alcohol
v) sulphur
vi) cellulose acetate (nail polish)
vii) Rust
viii) rubber
18) Complete the definition of the 'solubility of a solute in a solvent' by selecting the correct word in each case.
The solubility of a salute in a solvent at a particular temperature/pressure is the minimum/maximum amount of the solvent/solute in grams/ litres that will saturate/ dissolve in, 100 grams of the solvent/solution at that temperature.
19) An experimental procedure is involved in determining the solubility of a solute at t°C. The points A, B, C, D, E, F, G are the steps involved in determining the 'solubility of KCL' but the order is incorrect. Place the points in the correct order.
Solubility of a solute
A) Weigh a clean dry evaporiting dish and add the prepared saturated solution of KCl to it.
B) Add KCl crystals to distilled water, stir slowly till the crystals dissolve.
C) Heat the saturated in the evaporating dish to dryness and reweigh the dish with the residue.
D) Reweigh the evaporating dish with the saturated solution in it.
E) Make a saturated solution of KCl by adding more of the solute till no more of the solute dissolves.
F) Calculate the solubility of the solute at the noted temperature using the formula
Solubility= Wt of solute/Wt of solvent x 100
20) During the determination of the solubility of a solute the following calculations were noted.
a) dry evaporiting dish =Mg.
b) Evaporating dish+ saturated solution = M₁g.
c) Dish+ residue after heating above saturated solution to dryness = M₂g.
In terms of M, M₁ , M₂ complete the result of the solubility of the solute.
Solubility of solute = (_____ - ____)g/(____ - ___) g x 100 at t°C
21) With repres to 'solubility of potassium chloride in water' answer the following:
a) The solubility of KCl in water is 60g at 97°C. Explain the statement.
b) State one way by which the solubility of KCl in water can be increased.
c) Give reasons for the following:
i) Temperature is always specified when stating the solubility of a solute(e.g., KCl) in a solvent (eg., water)
ii) When 800 ml of saturated solution of salt 'X' is cooling from 75°C to 35°C a large amount of crystals are deposited out from the saturated solution on cooling, but when 800ml of a saturated solution of a salt 'Y' is cooled again from 75°C to 35°C the amount of crystals deposited out are much less.
d) 20 gram of saturated solution of salt at 60°C contains 5 gram of the salt. Calculate the solubility of the salt 'X' at 60°C.
e) A saturated solution of a salt 'Z' at 50°C is evaporated to dryness. if 50 gram of the saturated salt solution was used 20.5 gram of the residue was left behind . Calculate the solubility of the salt 'Z' at 50°C.
22) Solubility curves are graph of solubility (i.e., mass in grams of solute in 100g. of the solvent) against temperature in °C.
Deduction of solubilities of different solutes with respect to temperature can be referred from the solubility curves .
With reference to the following solutes given below, state which of the following solutes show:
i) an increase
ii) slight change
iii) decrease with rise in temperature.
solute solubility change with rise in
temperature
i) potasium nitrate
ii) copper sulphate
iii) calcium sulphate
iv) Potassium chloride
v) ammonium chloride
vi) sodium sulphate
23) Give reasons for the following:
a) solubility curves find utility in drug preparation by pharmacists .
b) solubility curves are used for extraction of essential chemicals from their natural resources.
c) purification and separation of various salutes can be carried out comparatively easily with the knowledge of the solubility graph or solubility curves.
24) Influence of pressure and temperature on the solubility of gases (in water)
A) complete the statement using the correct word.
An increase in pressure on the surface of water causes an increase/decrease in solubility of gas in water while an increase in temperature of water causes a decrease/ increase in the solubility of gas in water.
B) Give reasons for the following:
a) In the manufacture of soda, carbon dioxide is not dissolved at ordinary atmospheric pressure.
b) An aerated water bottle opens with a 'fizz'.
c) water tastes different before and after boiling.
d) The 'fizz' on opening a soda bottle is much less when the bottle is kept at ordinary temperatures and opened, than when a similar chilled bottle is opened.
25) Difference between the following:
a) crystal / seed crystal
b) crystallization/water of crystallization
c) hydrated crystal /anhydrated crystal
d) crystalline solids/ amorphous solids
26) Give reason for the following:
a) a hot saturated solution should be cooled slowly, followed by slow evaporation of the solution, when obtaining crystals from the solution.
b) Certain crystals eg., sodium chloride do not contain water of crystallization.
27) You are provided with
a) a saturated solution of notre at 90°C
b) a beaker
c) a glass rod
d) thread
e) a muslin cloth
Using the above, give the precise main steps for obtaining a well defined crystal of nitre. State two conditions for obtaining a large crystal.
28) The diagrams given below represents the action heat on hydrated copper sulphate crystals(A)
a) complete the equation for the action of heat on them.
b) Label X and Y in the diagram above.
c) State the changes which occur on heating the hydrated copper sulphate crystal with reference to (i) Before heating ii) after heating
A) colour of crystal
B) shape of crystal
C) nature of crystal
29) Match the chemical names of the crystals in column I with their common names in column II
COLUMN I
a) sodium carbonate
b) calcium sulphate
c) ferrous sulphate
d) copper sulphate
e) magnesium sulphate
f) sodium sulphate
g) calcium nitrate
h) sodium nitrate
i) potassium nitrate
j) Ammonium nitrate
COLUMN II
i) green vitriol
ii) Epsom salt
iii) Glauber's salt
iv) Chile salt petre
v) Blue vitriol
vi) Lime salt petre
vii) Washing soda
viii) gypsum
ix) Sal ammoniac
x) Nitre
Name one substance from Column I which is
A) Monohydrate
B) Dihydrate
C) Trihydrate
D) Pentahydrate
E) Hexahydrate
F) Heptaahydrate
G) Decahydrate
H) Anhydrous
(two examples )
30) complete the following terms using the correct word in each case :
a) An efflorescent substance is a crystalline /amorphous, anhydrous/hydrated salt which on exposure to the atmosphere loses/gains moisture partly or completely and changes into the amorphous/liquid state.
b) A deliquescent substances is a water soluble/insoluble salt which on exposure to the atmosphere absorbs/losers from the atmosphere, dissolves in the absorbed moisture and changes into amorphous /liquid state.
c) A hygroscopic substance absorbs /loses moisture from/to the atmosphere when exposed to it and undergoes/does not undergo any change in state.
31) Name the following:
a) A dehydrate efflorescent substance other than washing soda.
b) A deliquescent caustic alkali.
c) A solid hygroscopic substance used for drying Ammonia.
d) A hygroscopic substance used as a desiccanting agent.
e) a liquid which acts as a drying agent and a dehydrating agent.
f) A coloured hydrated efflorescent crystal.
g) A deliquescent crystal which is a chloride of a divalent metal.
h) A drying agent used for drying sulphur dioxide gas.
i) A basic oxide other than quicklime which is hydroscopic in nature.
j) A iron salt deliquescent in nature.
32) Give reason for the following:
a) Efflorescent is minimum during humid conditions while deliquescent is minimum during dry conditions .
b) Potassium chloride is not deliquescent and hence does not turn moist on exposure to the atmosphere. Common salt is also not deliquescent but turns moist on exposure to the atmosphere.
c) Hygroscopic substances differ from deliquescent substances.
No comments:
Post a Comment