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1.

`10mL` of `H_2O_2` solution (volume strength `= x`) requires `10mL` of `N//0.56 MnO_4^(ɵ)` solution in acidic medium. Hence`x` isA. `0.56`B. `5.6`C. `0.1`D. `10`

Answer» Correct Answer - D
`N of H_(2)O_(2)=`Volume strength `//5.6=x//5.6`
`mEq of H_(2)O_(2)-=mEq. Of MnO_(4)^(ɵ)`
`:. N_(1)V_(1)-=N_(2)V_(2)`
`x/5.6xx10mL-=1/5.6xx10 mL`
`:. X=10` volume strength
Discussion
2.

Give reason for the following a. The process `1/2H_(2(g))+e^(ɵ)toH_((g))^(ɵ)` is endothermic, yet ionic hydrides are known. b. A mixture of hydrazine and `H_(2)O_(2)` with `Cu(II)` catalyst is used as a rocket propellant. c. It is possible to remove completely the temporary hardness caused due to `Mg(HCO_(3))_(2)` by boiling.

Answer» a. The process `1/2 H_(2(g))+e^(ɵ)toH_((g))^(ɵ)`, i.e. formation of hydride ion is endothermic, yet group `1` and certain group `2` elements form ionic hydrides. This is due to the fact that the lattice energy released during the formation of ionic hydrides more than compensates the energy required for the formation of hydrides ion.
b. the reaction between hydrazines and `H_(2)O_(2)` using `Cu(II)` catalyst is highly exothermic and is accompanied by a large increases in the volume of the products, hence this mixutres is used as rocket propellant.
`H_(2)N-NH_(2(l))+2H_(2)O_(2(l))overset(Cu(II))toN_(2(g))+4H_(2)O_(g)`
c. Temprory hardness of `H_(2)O` caused due to `Mg(HCO_(3))_(2)` can be completely removed by boiling as soluble `Mg(HCO_(3))_(2)` is converted into insoluble `MgCO_(3)` which can be removed by filtration.
`Mg(HCO_(3))_(2)tooverset("Boil")toMgCO_(3)darr+CO_(3)uarr+H_(2)O`
Discussion
3.

How many allotropes of dihydrogen are known? What is their importance?

Answer» There are two allotrops of dihydrogen : (i) Ortho-hydrogen and (ii) Para-hydrogen The ortho-and para-hydrogen vary with temperature and have differences in their liquification and stability.
Discussion
4.

The adsorption of hydrogen by palladium is commonly known as ______.

Answer» Correct Answer - occulation
The adsorption of hydrogen by palladium is commonly known as occlusion.
Discussion
5.

Commet on the reactions of dihydrogen with (a) chlorine,(b) sodium and (c) copper (II) oxide.

Answer» dihydrogen reduces chlorine into chloride `(Cl^(ɵ))` ion and itself gets oxidised to `H^(o+)` ion by chlorine to form hydrogen chloride. An electron pair is shared between `H` and `Cl` leaving to the formation of a covalent molecule.
`H_(2g)+Cl_(2g)tounderset("Hydrogen chloride")(2HCl_(g))`
(b) Dihydrogen is reduced by sodium to form `NaH`. an electron is transfer from `Na` to `H` leading to the formation of an ionic compound, `Na^(o+)H^(ɵ)`.
red between `H` and `Cl` leaving to the formation of a covalent molecule.
`H_(2g)+2Na_(2g)tounderset("Sodium hydride")(2NaH_(s)`
(c) Dihydration reduces copper `(II)` oxide to copper in zero oxidation state and itself gets oxidised to `H_(2)O`, which is a covalent molecule.
`H_(2(g))+CuOtoCu_(s)+H_(2)O_((1))`
Discussion
6.

The mixture of hydrazine and hydrogen peroxides with a copper `(II)` catalyst is used as a rocket propellant.

Answer» `N_(4)H_(4)+2H_(2)O_(2)toN_(2)+4H_(2)O`
The mixtures of `N_(2)H_(4)` and `H_(2)O_(2)` ( in the presence of `Cu(II)` catalysts ) is used as a rocket propellants because of two reasons:
a. the reaction is highly exothermic.
b large volume of gases are envolved.
Discussion
7.

`D_O` is more polar than `H_2O.`

Answer» Correct Answer - T
True.
Discussion
8.

Protium oxide is the name given to `D_2O.`

Answer» Correct Answer - F
False. Protium oxide is `H_(2)O`
Discussion