Carbon on reaction with hot conc. $\mathrm{H}_{2} \mathrm{SO}_{4}$, gives two oxides along with $\mathrm{H}_{2} \mathrm{O}$. What is the nature of these two oxides?

Observe the following species.

(i) $\mathrm{NH}_3$

(ii) $\mathrm{AlCl}_3$

(iii) $\mathrm{SnCl}_4$

(iv) $\mathrm{CO}_2$

(v) $\mathrm{Ag}^{+}$

(vi) $ \mathrm{HSO}_{4}^{-} $

How many of the above species act as Lewis acids?

An organic compound containing phosphorous on oxidation with $\mathrm{Na}_2 \mathrm{O}_2$ gives a compound ' $X$ '. This ' $X$ ' when boiled with $\mathrm{HNO}_3$ followed by treatment with a reagent gives yellow precipitate $Y . X$ and $Y$ respectively are

Among the hydrides $\mathrm{NH}_3, \mathrm{PH}_3$ and $\mathrm{BiH}_3$, the hydride with highest boiling point is $X$ and the hydride with lowest boiling point is $Y$. What are $X$ and $Y$ respectively?