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.
(a, b, c) Metallic hydrides are non-stoichiometric hydrides. They conduct heat and electricity. Ionic hydrides conduct electricity only in molten or aqueous state.
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.
Consider the reaction of water with F2 and suggest, in terms of oxidation and reduction, which species are oxidised/reduced ?
Why does H+ ion always get associated with other atoms or molecules?
(a) Ionisation enthalpy of hydrogen resembles that of alkali metals.
(b) Its reactivity is similar to halogens.
(c) It resembles both alkali metals and halogens.
(d) Loss of an electron from hydrogen atom results in a nucleus of very small size as compared to other atoms or ions. Due to small size it can not exist freely.
Do you expect different products in solution when aluminium (III) chloride and potassium chloride treated separately with (i) normal water (ii) acidified water (iii) alkaline water? Write equation wherever necessary.
Which of the following reactions increases production of dihydrogen from synthesis gas?
Hardness of water may be temporary or permanent. Permanent hardness is due to the presence of
(a) Chlorides of Ca and Mg in water
(b) Sulphate of Ca and Mg in water
(c) Hydrogen carbonates of Ca and Mg in water
(d) Carbonates of alkali metals in water.
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.
Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.
(a) How is dihydrogen prepared from water by using a reducing agent?
(b) Give the industrial use of dihydrogen which depends upon heat liberated when it bums.
Which of the following equatibns depicts the oxidizing nature of H202?
(a) 2Mn0–4 + 6H+ + 5H202 → 2Mn2+ + 8H20 + 502
(b) 2Fe3+ + 2H+ + H202 → 2Fe2+ + 2H20 + 02
(c) 2I– + 2H+ + H202 → I2 + 2H20
(d) KI04 + H202 → KI03 + H20 + 02
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?
Which of the following statements are correct?
(a) Elements of group 15 form electron deficient hydrides.
(b) All elements of group 14 form electron precise hydrides.
(c) Electron precise hydrides have tetrahedral geometries.
(d) Electron rich hydrides can act as Lewis acids.
Explain the following:
(i) Temporary hardness can remove by boiling
(ii) Soft water lathers with soap but hard water not.
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.
What do you understand by (i) Electron-deficient (ii) Electron-precise (iii) Electron-rich compounds of hydrogen? Provide justification with suitable examples.
Do you expect the carbon hydride of type Cn H2n+2 to act as ‘Lewis’ acid or base? Justify your answer.
Saline hydrides are known to react with water violently producing fire. Can C02, a well known fire extinguisher, be used in this case? Explain.
Write chemical reactions to justify that hydrogen peroxide can function as an oxidising as well as reducing agent.
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.
Hydrogen peroxide is obtained by‘the electrolysis of _______.
(a) water
(b) sulphuric acid
(c) hydrochloric acid
(d) fused sodium peroxide
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.
Melting point, enthalpy of vapourisation and viscosity data of H20 and D20 are given below:
| H2o | D2o | |
| Boiling point / K | 373.0 | 374.4 |
| Enthalpy of vapourisation at (373 K)/ kJ mol-1 | 40.66 | 41.61 |
| Viscosity/centipoise | 0.8903 | 1.107 |
On the basis of this data, explain in which of these liquids intermolecular forces are stronger?
Describe the bulk preparation of dihydrogen by electrolytic method. What is the role of an electrolyte in this process?
What characteristics do you expect from an electron-deficient hydride with respect to its structure and chemical reaction?
Knowing the properties of H2O and D2O, do you think D2O can be used for drinking purpose.
Which gas is evolved when Mg3N2 (Magnesium nitride) is treated with H2O? Give chemical reaction.
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.
Dihydrogen can be prepared on commercial scale by different methods. In its preparation by the action of steam on hydrocarbons, a mixture of CO and H2 gas is formed. It is known as _____ .
(a)water gas
(b) syn gas
(c) producer gas
(d) industrial gas
Which of the following statements about hydrogen are correct?
(a) Hydrogen has three isotopes of which protium is the most common.
(b) Hydrogen never acts as cation in ionic salts.
(c) Hydrogen ion, H+, exists freely in solution.
(d) Dihydrogen does not act as a reducing agent.
Discuss the consequences of high enthalpy of H-H bond, in terms of chemical reactivity of dihydrogen.
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.
