Chemistry
Give reasons for the following:
(a) Hydrogen can be used as a fuel.
(b) Though hydrogen is lighter than air it cannot be collected by downward displacement of air.
(c) A pop sound is produced when hydrogen gas is burnt.
(d) Helium has replaced hydrogen in weather observation balloons.
(e) Nitric acid is not used for the preparation of hydrogen gas.
Hydrogen
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Answer
(a) Hydrogen has high heat of combustion and is pollution free so it is used as a fuel. Liquid hydrogen is used as a rocket fuel.
(b) Though hydrogen is lighter than air it cannot be collected by downward displacement of air because a mixture of hydrogen and air can lead to an explosion so it is not safe to collect hydrogen gas by this method.
(c) A pop sound is produced when hydrogen gas is burnt because of the presence of impurities in it.
(d) Hydrogen gas is highly inflammable in nature, so it is replaced by helium for filling in weather forecasting balloons.
(e) Nitric acid is a strong oxidizing agent (even when it is dilute). It oxidises hydrogen gas converting it into water which defeats the purpose. Hence, nitric acid is not used for the preparation of hydrogen gas.
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Related Questions
Indicate which of the following statements are true and which are false:
(a) Hydrogen molecule is monovalent.
(b) The removal of hydrogen from a substance is called reduction.
(c) Nitric acid cannot be used to prepare hydrogen by its action on active metals.
(d) The reaction between hydrogen and nitrogen to form ammonia is reversible.
(e) Zinc can liberate hydrogen from water, acid and alkali solution.
(f) Hydrogen is combustible as well as a supporter of combustion.
(g) Hydrogen gas is easily liquefiable.
Complete and balance the following equations:
(a) H2 + ……………….. ⟶ 2HCl
(b) H2 + S ⟶ ……………………
(c) Zn + ……………. ⟶ ZnCl2 + H2
(d) CuO + ………….. ⟶ Cu + ………….
(e) Fe + H2O ⟶ …………….. + ……………
(f) K + H2O ⟶ ……………… + ……………
Name the following:
(a) Two metals which give hydrogen with cold water.
(b) A metal which liberates hydrogen only when steam is passed over red hot metal.
(c) The process in which oxygen is added or hydrogen is removed.
(d) A metallic oxide which can be reduced into metal by hydrogen.
(a) Name the chemicals required to prepare hydrogen gas in the laboratory.
(b) Give a balanced chemical equation for the reaction.
(c) Draw a neat and well-labelled diagram for the laboratory preparation of hydrogen.
(d) How is hydrogen gas collected? Why?