# How many nitrogen atoms are present in a sample of 1,983 hydrogen atoms, if ammonia is a compound consisting of a 1:3 ratio of nitrogen and hydrogen atoms?

The answer is $661$ atoms of $N$.
Since ammonia ($N {H}_{3}$) has a $1 : 3$ ratio of Nitrogen to Hydron atoms, and since the number of $H$ atoms is 1983, the number of $N$ atoms is
$1983$ $H$ $a t o m s$ $\cdot \frac{1 a t o m N}{3 a t o m s H} = 661$ atoms $N$.