Question

A metal which does not react with nitrogen is:

• A. $Li$
• B. $K$
• C. $Ca$
• D. $Mg$

Answer 1

The correct option is B $K$

Only $K$ doesn't react with nitrogen directly, while others do.
The reactions are:

$Li+N_2\to L{i}_{3}N$

$Mg+N_2\to M{g}_3{N}_2$

$3Ca\left(s\right)+N_2\left(g\right)\to C{a}_3{N}_2\left(s\right)$

Lithium is the smallest atom among alkali metals. ... When Lithium reacts with nitrogen gas at room temperature (N2), it forms Lithium Nitride (Li3N) which is stable, because the lattice energy released from the formation of Li3N is high enough to make the overall reaction exothermic.

As K is a group 1 element, it will not react with N${}_2$

Hence, the correct option is $\text{B}$