JEE Main 2022 — p Block Elements (Group 15, 16, 17 & 18) Question with Solution

Thermal decomposition of ammonium dichromate ${\left({\mathrm{NH}}_4\right)}_2{\mathrm{Cr}}_2{\mathrm{O}}_7$ on heating gives ${\mathrm{N}}_2, {\mathrm{Cr}}_2{\mathrm{O}}_3$ and ${\mathrm{H}}_2\mathrm{O}$ as follows:

${\left({\mathrm{NH}}_4\right)}_2{\mathrm{Cr}}_2{\mathrm{O}}_7\stackrel{∆}{\to }{\mathrm{N}}_2+{\mathrm{Cr}}_2{\mathrm{O}}_3+4{\mathrm{H}}_2\mathrm{O}$

$2{\mathrm{KMnO}}_{4\left(\mathrm{s}\right)}+16\mathrm{HCl}\left(\mathrm{aq}\right)\to 2\mathrm{KCl}\left(\mathrm{aq}\right)+2{\mathrm{MnCl}}_{2\left(\mathrm{aq}\right)}+8{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)+5{\mathrm{Cl}}_{2\left(\mathrm{g}\right)}$

The reaction of Aluminium with Sodium hydroxide $(\mathrm{Al}+\mathrm{NaOH})$ gives a salt and Hydrogen gas.

$2\mathrm{Al}\left(\mathrm{s}\right)+2\mathrm{NaOH}\left(\mathrm{l}\right)+6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to 2\mathrm{Na}\left[\mathrm{Al}{\left(\mathrm{OH}\right)}_4\right]\left(\mathrm{s}\right)+3{\mathrm{H}}_2\left(\mathrm{l}\right)$

On heating sodium nitrate it undergoes decomposition reaction and liberates oxygen and convert into sodium nitrite.