Answer
$\frac{13.90}{1}$
Work Step by Step
As we know that the atomic ratio of nitrogen to hydrogen is $1:3$, so we divide the mass of $N$ by $\frac{1}{3}$ of the mass of the hydrogen in order to find the relative mass of nitrogen.
$\frac{Atomic \space mass \space of \space N }{Atomic \space mass \space of \space H}=\frac{7.933g}{\frac{1}{3}\times 1.712g}=\frac{13.90}{1}$
