Question

Ammonia gas is prepared by:

• A. Heating ammonium dichromate
• B. Heating ammonium nitrate
• C. Heating ammonium sulphate
• D. Heating ammonium perchlorate

Answer 1

The correct option is C Heating ammonium sulphate

Ammonium salts decompose readily on heating. Now if the anions of the salts are not particularly oxidising such as $C{O}_3^{2-}$, $S{O}_4^{2-}$ then on heating ammonia is evolved.
$(N{H}_4{)}_{2}S{O}_4\stackrel{\text{heat}}{\to }2N{H}_3+H_{2}S{O}_4$
Oppositely if the anions are more oxidising such as $Cl{O}_4^{-},C{r}_2{O}_7^{2-},N{O}_3^{-}$ then $N{H}_4^{+}$ is oxidised to $N_2$ or $N_{2}O$

$(N{H}_4{)}_{2}C{r}_2{O}_7\stackrel{\text{heat}}{\to }{N}_2+4H_{2}O+C{r}_2{O}_3$
$N{H}_{4}N{O}_3\stackrel{\text{heat}}{\to }{N}_{2}O+2H_{2}O$
$N{H}_{4}Cl{O}_4^{-}\stackrel{\text{heat}}{\to }4HCl+2N_2+5O_2+6H_{2}O$