Chemistry

Hydrogen

Question:

Which of the following statements are correct?
(a) Metallic hydrides are deficient of hydrogen.
(b) Metallic hydrides conduct heat and electricity.
(c) Ionic hydrides do not conduct electricity in solid state.
(d) Ionic hydrides are very good conductors of electricity in solid state.

Answer:

(a, b, c) Metallic hydrides are non-stoichiometric hydrides. They conduct heat and electricity. Ionic hydrides conduct electricity only in molten or aqueous state.

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Hydrogen

Q 1.

Show how H2O2 junctions both as a reducing and as an oxidising agent.

Q 2.

Describe the usefulness of water in biosphere and biological systems.

Q 3.

Which type of hydrides are generally non-stoichiometric in nature?

Q 4.

Complete the following reactions:
cbse-class-11th-chemistry-solutions-chapter-9-hydrogen-23

Q 5.

Which of the following equatibns depicts the oxidizing nature of H202?
(a) 2Mn04 + 6H+ + 5H202 → 2Mn2+ + 8H20 + 502
(b) 2Fe3+ + 2H+ + H202 → 2Fe2+ + 2H20 + 02
(c) 2I + 2H+ + H202 → I2 + 2H20
(d) KI04 + H202 → KI03 + H20 + 02

Q 6.

What is the cause of bleaching action of H2O2?

Q 7.

What type of elements form interstitial hydrides?

Q 8.

Dihydrogen reacts with dioxygen (02) to form water. Write the name and formula of the product when the isotope of hydrogen which has one proton and one neutron in its nucleus is treated with oxygen. Will the reactivity of both the isotopes be the same towards oxygen? Justify your answer.

Q 9.

Give two advantages of using hydrogen over gasoline as a fuel.

Q 10.

If same mass of liquid water and a piece of ice are taken, then why is the density of ice less than that of liquid water?

Q 11.

How can saline hydrides remove traces of water from organic compounds?

Q 12.

How is  heavy water prepared? Compare its physical properties with those of ordinary water.

Q 13.

What is zeolite?

Q 14.

Which compounds cause temporary hardness of water?

Q 15.

Write the names of isotopes of hydrogen. What is the mass ratio of these isotopes?

Q 16.

What is meant by ‘demineralised water’ and how can it be obtained?

Q 17.

Account for the following:
(a) Can phosphorus with electronic configuration 3s2 3p3 form PH5?
(b) Water is responsible for moderation of body temperature. How?
(c) Hard water is not suitable for boilers as well as for laundary.

Q 18.

Discuss the consequences of high enthalpy of H-H bond, in terms of chemical reactivity of dihydrogen.

Q 19.

What do you understand by (i) Electron-deficient (ii) Electron-precise (iii) Electron-rich compounds of hydrogen? Provide justification with suitable examples.

Q 20.

Arrange the following:
(i) CaH2, BeH2 and TiH2 in order of increasing electrical conductance.
(ii) LiH, NaH and CsH in order of increasing ionic character.
(iii) H-H, D—D and F—F in order of increasing bond dissociation enthalpy.
(iv) NaH, MgH2 and H2O in order of increasing reducing property.

Q 21.

Compare the structures of H2O and H2O2

Q 22.

What causes the temporary and permanent hardness of water?

Q 23.

Write chemical reactions to justify that hydrogen peroxide can function as an oxidising as well as reducing agent.

Q 24.

What is water gas? How is it prepared?

Q 25.

Name a substance which can oxidise H2O2

Q 26.

What is the use of hydrogen in the manufacture of Vanaspati Ghee?

Q 27.

What are interstitial hydrides? Give two examples.

Q 28.

Hydrogen resembles halogens in many respects for which several factors are responsible. Of the following factors which one is most important in this respect?
(a) Its tendency to lose an electron to form a cation.
(b) Its tendency to gain a single electron in its valence shell to attain stable electronic configuration.
(c) Its low negative electron gain enthalpy value.
(d) Its small size.

Q 29.

Consider the reactions
(A) H202 + 2HI → I2 + 2H20
(B) HOCl + H2O2 → H30+ + Cl‑ + 02
Which of the following statements is correct about H202 with reference to these reactions? Hydrogen peroxide is   _______      
(a) an oxidizing agent in both (A) and (B)
(b) an oxidizing agent in (A) and reducing agent in (B)
(c) a reducing agent in (A) and oxidizing agent in (B)
(d) a reducing agent in both (A) and (B)

Q 30.

The oxide that gives H202 on treatment with dilute H2S04 is
(a) Pb02
(b) Ba02 -8H20
(c) Mn02
(d) Ti02

Q 31.

When sodium peroxide is treated with dilute sulphuric acid, we get .
(a) sodium sulphate and water
(b) sodium sulphate and oxygen
(c) sodium sulphate, hydrogen and oxygen
(d) sodium sulphate and hydrogen peroxide.

Q 32.

Which of the following statement(s) is/are correct in the case of heavy water?
(a) Heavy water is used as a moderator in nuclear reactor.
(b) Heavy water is more effective as solvent than ordinary water.
(c) Heavy water is more associated than ordinary water.
(d) Heavy water has lower boiling point than ordinary water.

Q 33.

Some of the properties of water are described below. Which of them is/are not correct?
(a) Water is known to be universal solvent.
(b) Hydrogen bonding is present to a large extent in liquid water.
(c) There is no hydrogen bonding in the frozen state of water.
(d) Frozen water is heavier than liquid water.

Q 34.

How can production of hydrogen from water gas be increased by using water gas shift reaction?

Q 35.

What are metallic/interstitial hydrides? How do they differ from molecular hydrides?

Q 36.

Discuss briefly de-mineralisation of water by ion exchange resin.

Q 37.

Write one chemical reaction for the preparation of D202.

Q 38.

Rohan heard that instructions were given to the laboratory attendant to store a particular chemical, i.e., keep it in the dark room, add some urea in it, and keep it away from dust. This chemical acts as an oxidizing as well as a reducing agent in both acidic and alkaline media. This chemical is important for use in the pollution control treatment of domestic and industrial effluents.
(i) Write the name of this compound.
(ii) Explain why such precautions are taken for storing this chemical.

Q 39.

Why does hydrogen occur in a diatomic form rather than in a monoatomic form under normal conditions?

Q 40.

Describe the bulk preparation of dihydrogen by electrolytic method. What is the role of an electrolyte in this process?

Q 41.

What characteristics do you expect from an electron-deficient hydride with respect to its structure and chemical reaction?

Q 42.

Do you expect the carbon hydride of type  Cn H2n+2  to act as ‘Lewis’ acid or base? Justify your answer.

Q 43.

What do you understand by the term ‘non-stoichiometric hydrides’? Do you expect this type of hydrides to be formed by alkali metals? Justify your answer.

Q 44.

Consider the reaction of water with F2 and suggest, in terms of oxidation and reduction, which species are oxidised/reduced ?

Q 45.

Complete the following chemical reactions.
(i) PbS(s) + H2O2 (aq) ————->
(ii) MnO4 (aq) + H2O2 (aq) ————->
(iii) CaO(s) + H2O(g) ————->
(iv) AlCl3(g) + H2O(l)————->
(v) Ca3N2(S) + H2O(l) ————->
Classify the above into (a) hydrolysis, (b) redox and (c) hydration reactions.

Q 46.

What properties of water make it useful as a solvent? What types of compound can it (i) dissolve (ii) hydrolyse?

Q 47.

What is the importance of heavy water with regard to nuclear power generation ?

Q 48.

Write two uses of interstitial hydrides.

Q 49.

Give an example of an ionic hydride and a covalent hydride:

Q 50.

What is perhydrol?