Question:
Two elements A and B have similar chemical properties. They don't form solid hydrogencarbonates, but react with nitrogen to form nitrides. A and B, respectively, are :
Correct Option: , 4
Solution:
$\mathrm{Li}$ and $\mathrm{Mg}$ do not form solid bicarbonate, but react with $\mathrm{N}_{2}$ to give nitrides.
$6 \mathrm{Li}+\mathrm{N}_{2} \stackrel{\Delta}{\longrightarrow} 2 \mathrm{Li}_{3} \mathrm{~N}$
$3 \mathrm{Mg}+\mathrm{N}_{2} \stackrel{\Delta}{\longrightarrow} \mathrm{Mg}_{3} \mathrm{~N}_{2}$