pBlock ElementsII 1 Question 104
101. Explain the following in one or two sentences.
(i) Magnesium oxide is used for the lining of steel making furnace.
(ii) The mixture of hydrazine and hydrogen peroxide with a copper (II) catalyst is used as a rocket fuel.
(iii) Orthophosphorous acid is not tribasic acid.
(iv) The molecule of magnesium chloride is linear, whereas that of stannous chloride is angular.
$(1987,4 \mathrm{M})$
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Solution:
- (i) $\mathrm{MgO}$ is used for the lining of steel making furnace because it forms slag with impurities, and thus helps in removing them from iron.
(ii) The mixture of $\mathrm{N}{2} \mathrm{H}{4}$ and $\mathrm{H}{2} \mathrm{O}{2}$ (in presence of $\mathrm{Cu}$ (II) catalyst) is used as a rocket propellant because the reaction is highly exothermic and large volumes of gases is evolved.
$$ \mathrm{N}{2} \mathrm{H}{4}(l)+2 \mathrm{H}{2} \mathrm{O}{2}(l) \longrightarrow \mathrm{N}{2}(g)+4 \mathrm{H}{2} \mathrm{O}(g) $$
(iii) In orthophosphorus acid $\left(\mathrm{H}{3} \mathrm{PO}{3}\right)$ only two of the three $\mathrm{H}$ are replaceable as
(Only $\mathrm{H}$ of $-\mathrm{OH}$ are acidic)
(iv) In $\mathrm{MgCl}{2}, \mathrm{Mg}$ is $s p$-hybridised while in $\mathrm{SnCl}{2}, \mathrm{Sn}$ is $s p^{2}$-hybridised with a lone pair at $\mathrm{Sn}$. Hence, $\mathrm{MgCl}{2}$ is linear while $\mathrm{SnCl}{2}$ is angular.
