Question

Among $N{H}_3,HN{O}_3,Na{N}_3$ and $M{g}_3{N}_2$. Find the number of molecules having nitrogen in negative oxidation state

Answer 1

Answer: 3

Calculating the oxidation state of nitrogen in given molecules;
Oxidation state of $N$ in $N{H}_3$ is
$x+3\times (+1)=0$ or $x=-3$
Oxidation state on $N$ in $NaN{O}_3$ is
$1+x+3\times (-2)=0$ or $x=+5$
Oxidation state of $N$ in $Na{N}_3$ is
$+1+3x=0$ or $x=-\frac{1}{3}$
Oxidation state of N in $M{g}_3{N}_2$ is
$3\times 2+2x=0$ or $x=-3$
Thus 3 molecules (i.e. $N{H}_3,Na{N}_3$ and $M{g}_3{N}_2$, have nitrogen in negative oxidation state