1) Name or state with reference to hydrogen- the first element of the periodic table.
a) The period of the periodic table to which the element hydrogen belongs.
b) The two subgroups of the periodic table in which hydrogen can be placed.
c) The element in the period-3 which is electropositive and shows similarity to hydrogen.
d) The element in period-4 which is electronegative and shows similarity to hydrogen.
e) An element in period-2 which has the same atomicity as hydrogen.
f) An element which combines with both hydrogen and halogen forming covalent compounds .
g) An electrovalent compound formed from an element in period-3 and hydrogen.
h) A covalent gases compound formed from an element in period-3 and hydrogen.
i) An oxide of hydrogen which is neutral in nature.
j) The number of shared pairs of electrons in a diatomic molecule of hydrogen.
k) A nonmetallic element in group IA of the periodic table.
2) Complete the following sentences by filling in the blanks with the appropriate word/s.
a) The first element hydrogen of the periodic table shows similarity with___ metals of group I A and_____ of a group VIIA.
b) Hydrogen shows electropositive character. Elements in group I A are considered electropositive since they have a tendency to____ one electron from its valence shell.
c) Hydrogen also shows electronegative character. Elements in group VIIA are considered electronegativity since they have a tendency to ____one electron forming an electronegative element.
d) The electronic configuration of the element in period-3 which has the same number of valence electrons as hydrogen is____.
e) The element in group I A which has one electron less than the noble gas present in period-1 of the periodic table is ____.
f) Hydrogen is a diatomic molecule which has two atoms linked by a____ covalent bond. The element in group VIIA which is also diatomic and exists in the liquid state at room temperature is____
g) Halides of hydrogen and alkali metal yield ____ions in aqueous solution. During electrolysis these ions are discharged at the negative electrode i.e., cathode.
3) Give reasons for the following:
a) Hydrogen can be positioned in group I A and group VIIA of the periodic table.
b) Hydrogen can be represented as H¹⁺ or as H¹⁻
4) Match the points pertaining to the occurrence and discovery of hydrogen in column I with the concluding facts in column II
Column I
A) Lavoisier in 1783 established the name "hydrogen".
B) Hydrogen does not occur
C) Hydrogen is present in traces in
D) A compound, one ninth by mass of which is hydrogen in the combined state is
Column II
a) the atmosphere around the sun and stars.
b) water
c) meaning 'water producer'
d) in the free state on earth.
5) Hydrogen is prepared from cold water, boiling water or steam by reaction with certain metals involving potassium, sodium, calcium, magnesium, aluminium, zinc , iron. Complete and balance the equation for the reactions of the above metals with water by substituting the correct symbols in each case.
a) Reaction with cold water
i) X + H₂O--> XOH + H₂ (X-burns in air with a lilac flame)
ii) Y + H₂O --> YOH + H₂. (Y-burns in air with a golden yellow flame)
iii) Z + H₂O --> Z(OH)₂ + H₂ (Z-burns in air with a brick red flame)
b) Reaction with boiling water or steam
i) Q + H₂O --> QO + H₂. (QO- is a basic oxide)
ii) R + H₂O---> RO + H₂. (RO- is an amphoteric oxide)
iii) S + H₂O ---> S₂O₃+ H₂. (S-is a trivelent metal)
iv) T+ H₂O <=> + H₂ (Reaction of T with steam is reversible)
6) Hydrogen is also prepared by the action metals on dilute acids on alkalis. The metal is converted to its salt and gases hydrogen is liberated .
Complete and balance the equations for the conversions of the following metals to their salts using an acid or an alkali.
Metal Acid/Alkali Salt Hydrogen
1. Mg + ____ -> ____(magnesium chloride)+ H₂
2. Al+ _____ -> ____(Aluminium Sulphate)+ H₂
3. Fe + ___ -> ____ (ferrous chloride)+ H₂
4. Zn + ____ -> ____(sodium zincate)+ H₂
5. PB + ___ -> ____ (sodium plumbate) + H₂
6. Al + ____ -> ____(Sodium aluminate)+ H₂
7. Al + ____ -> ____(Potassium aluminate) + H₂
7) Give reasons for the following:
a) Sodium and potassium are not preferred as the starting metals in the preparation of hydrogen from cold water.
b) Amalgamated sodium can be used in place of sodium in the above preparation.
c) Reaction of magnesium or aluminium with boiling water is comparatively slow and the reaction later comes to a stop.
d) The reaction in (c) above can be made to proceed again by passage of steam over the red hot metal .
e) Reaction of magnesium with water moves in the forward direction only while that of iron with water (steam) is a reversible reaction.
f) Dilute nitric acid is generally not used in the preparation of hydrogen from metals, however , magnesium reacts with very dilute nitric acid at low temperature liberating hydrogen.
g) Dilute acids react with metals liberating hydrogen, even then lead is not used in the reaction with dilute hydrochloric or sulphuric acid.
8) Name the following:
a) A metal which reacts explosively with cold water liberating hydrogen.
b) A metal alloyed with the sodium to give amalgamature sodium.
c) A metal which reacts very slowly with boiling water to liberate hydrogen.
d) A trivalent metal which displaces hydrogen from dilute sulphuric acid.
e) The salt formed when iron reacts with dilute hydrochloric acid displacing hydrogen from it.
f) A metal which reacts with dilute hydrochloric acid to form a salt insoluble in cold water but soluble in hot water.
g) The salt formed when zinc reacts with caustic potash liberating hydrogen.
h) A metal other than magnesium which reacts with very dilute nitric acid liberating hydrogen.
i) A metal which reacts with cold water forming a turbid solution.
j) Two metals which do not take displace hydrogen from dilute acids.
9) Preparation of hydrogen- Laboratory method
The above diagram represents the laboratory preparation of hydrogen by action of dilute hydrochloric acid on zinc. Complete and balanced equation for the above laboratory preparation of hydrogen.
_______+ ______ -> ____+ H₂
ᵐᵉᵗᵃˡ (ᵈᶦˡ) (ˢᵃˡᵗ)
10) Give reasons for the following:
a) Granulated zinc is preferred to pure zinc for the reaction with dilute acid.
b) The initial gas bubbles of hydrogen are allowed to escape out before the actual collection of hydrogen gas.
c) Highly electropositive metals are not used in place of zinc in the preparation.
d) Concentrated hydrochloric acid is not preferred to dilute acid for reaction with zinc in the laboratory preparation.
e) A naked flame is never brought near the apparatus used in the laboratory preparation.
f) The lower end of the thistle funnel should dip below the level of the dilute acid in the flask.
g) Traces of copper (II) sulphate maybe added to the reaction medium.
h) Hydrogen gas prepared in the laboratory has a peculiar smell.
i) Hydrogen is lighter than air, even then it is not collected over air, but by downward displacement of water.
11) Pure hydrogen is prepared by passage of the gas through various solution which respectively absorb each impurity . Match the impurity with the solution which absorbs it.
Impurity
A. Arsine (AgH₃)
B. Phosphine (PH₃)
C. Hydrogen sulphide (H₂S)
D. Nitrogen dioxide (NO₂)
E. Sulphur dioxide (SO₂)
F. Moisture
Removed by
i) Potassium hydroxide solution
ii) Fused calcium chloride
iii) Silver nitrate solution
iv) Lead nitrate solution
12) Complete the table pertaining to the production of hydrogen by the Bosch process involving three main steps.
Step I production of water gas
X + H₂O ---°C--> XO+ H₂ ∆
• Equation: ____
• X is white/red hot ____
• Temperature of the reaction_______°C.
• Reaction is____ (exothermic/endospermic).
• Resultant product of the reaction is water gas a mixture of____[XO] and hydrogen in the ratio ____: ___.
Step II Reduction of steam by hydrogen by XO
XO + H₂ + H₂O ---°C--> XO₂+ 2H₂O. ∆
• Equation : ________
• The reactants are water gas and____( limited/excess) steam.
• Temperature of the reaction is around____ °C.
• The catalyst used is ____(Z₂O₃).
• The catalyst also used other than the one used in above is ___
• _____(XO) is____(oxidised /reduced) to ____(XO₂) with a further yield of hydrogen in the reaction in Step II.
• Reaction in Step II is ____(exothermic/endothermic).
Step III Removal of carbon monoxide and carbon dioxide from the above mixture
using X , Y and Z how are the gases separated
X= Potassium hydroxide,
Y= water
Z= Ammoniacal cuprous chloride
Solution Gas absorbed Equation a method then the one use ever for manufacture of X= KOH ______ _______
Y= water _______ _______
Z= Ammoniacal ____ _______
13) A method other than the one used above for manufacture of hydrogen involves electrolysis of a neutral[X] as the starting reactant.
a) Name the neutral liquid [X]
b) Give the equation for the electrolysis of the same.
c) Name the electrode at which hydrogen is liberated.
d) State the reason for acidification of the neutral liquid.
e) Name another solution which on electrolysis liberates hydrogen as a bi-product.
14) Complete the table by selecting the correct word in each case.
Property of hydrogen
1. Comparative density a) 1.1 times heavier than air; b) as heavy as air; c) 14.4 times less than dense than air.
2. Solubility in water a) Fairly ; b) Highly; c) Slightly soluble
3. Liquification a) easy to liquefy; b) difficult to liquefy
4) Combustibilty a) non-combustible but supporter of combustion; b) combustible but non-supporter of combustion
5) Nature a) acidic ; b) basic ; c) neutral to litmus
15) Using hydrogen as one of the reactants how would you obtain: (Write the Equation)
a) A neutral liquid using a neutral gas.
b) An acidic gas using another acidic gas.
c) A basic gas using an unreactive gas.
d) A acidic gas using vapours of a non metal.
e) a9 hydride using a monovalent active metal.
16) Hydrogen reduces certain metallic oxides to free metals. Give an equation of each of the following reductions.
Metallic oxide
a) A black basic oxide.
b) A yellow amphoteric oxide
c) An oxide of iron.
17) Name the following:
a) The condition in which equal volumes of hydrogen and chlorine react slowly producing hydrogen chloride.
b) The catalyst and promoter used in the conversion of Nitrogen to ammonia using H₂.
c) The state of sulphur which reacts with hydrogen forming hydrogen sulphide.
d) The phenomenon due to which certain metals eg., palladium absorbs large volumes of hydrogen on their surface.
e) A catalyst used in hydrogenation reactions.
f) A product manufacturered using the process of hydrogenation of iols.
g) The product of oxidation of hydrogen formed during reproduction of zinc oxide by hydrogen.
h) The product formed when pure hydrogen burns in oxygen.
i) A metallic oxide which is not reduced to its metal by hydrogen.
j) Two colourless gaser one of which is hydrogen which combines under suitable conditions to give another colourless gas.
18) Give reasons for the following:
a) Nickel finds application in hydrogenation reactions hydrogenation of oil.
b) Passage of hydrogen through vegetable oils under suitable conditions results in their solidification.
c) Pure hydrogen burns quietly while hydrogen-air mixture does not.
d) Hydrogen can be separated from a mixture of hydrogen and carbon dioxide by liquification.
19) The table below represents the metal activity series with the most active metal at the top of the series and the least active below. Name the following:
K 1. Reacts violently with water liberating hydrogen.
Na 2. Does not react with steam or Dil. HCl .
Ca 3. Is divalent and displaces hydrogen from water.
Mg 4. Displaces hydrogen from caustic soda but does not react with dil. HCl
Al
Zn 5. Displaces hydrogen from very dilute nitric acid.
Fe 6. Does not react with dil. sulphuric acid but reacts with steam liberating hydrogen.
SN
PB 7. Displaces hydrogen from dil. HCl and dil. H₂SO₄ but not from dil. nitric acid.
[H]
Cu 8. Reacts violently when placed in any dilute acid.
Hg 9. Displaces hydrogen from cold water forming a colourless solution.
Ag
Au 10. Displaces hydrogen from steam leaving behind an amphoteric residue.
Pt
20) Experimental verification of physical and chemical properties of Hydrogen.
Match the property of hydrogen given below relating to the experimental A, B or C
A) Property of hydrogen Experiment A, B, C
a) Hydrogen is combustible but does not support combustion
b) Combustion of hydrogen produces water.
c) Hydrogen is lighter than air.
B) In experiment A:
a) How would you prove that jar 'B' contains 'hydrogen-air' mixture after the lid between jar 'A' containing hydrogen and jar 'B' is removed .
b) If jar 'A' contains 'carbon dioxide' instead of hydrogen what would the empty jar 'B' now contains after removal of the lid in between. Give reasons.
c) If jar 'A' contains hydrogen and a jar 'B' contains carbon dioxide and the lid between them is removed what would jar 'A' now contain. Give reasons.
C) In Experiment B:
Give reason for the following:
a) The candle when pushed slowly inside the jar containing hydrogen gets extinguished.
b) The candle when brought near the mouth of the jar contain hydrogen gets rekindleed again and start burning .
In Experiment C
Give reasons for the following:
a) Anhydrous calcium chloride is placed in the U-tube.
b) Pure hydrogen burns with a characteristic flame in the hard glass tube forming water but the observation differs if a premixed mixture of hydrogen and air is burnt.
21) The diagram represent experimentally an important chemical property of Hydrogen 
a) State the chemical property
b) The above property is represented by the equation:
CuO + H₂--> Cu + H₂O
Name the following:
i) The reducing agent.
ii) The reduced product.
iii) The oxidised product
c) Give reasons for the following:
a) The above reaction is called a 'reduction reaction'
b) Hydrogen is continued to pass even after the heating stopped .
c) A flame is lit at the end of the jet tube 'A'.
22) Give reasons for the following:
a) Hydrogen gas can be tested by its combustibility in air.
b) if a jar containing hydrogen-carbon dioxide mixture is placed over an empty porous pot, the porous pot gets filled with hydrogen initially.
c) Two gas jars, one containing 'oxygen' and other 'hydrogen' can be identified with a glowing splinter , but not with a moist litmus paper.
d) Hydrogen finds application as a constituent of important fuels.
e) Hydrogen gas was initially used to study whether conditions.
f) Extraction of certain metals from their oxides may be carried out using hydrogen.
g) Oxy-hydrogen flames used in welding and cutting of metals produce high school temperatures.
h) Hydrogen finds application in the conversion of palm oil to solid fats.
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