Question:
The mass percentage of nitrogen in histamine is____________ .
Solution:
(37.84)
Molecular formula of histamine is $\mathrm{C}_{5} \mathrm{H}_{9} \mathrm{~N}_{3}$
Molecular mass of histamine
$=5 \times 12+9 \times 1+3 \times 14=111$
Mass percentage of nitrogen in histamine
$=\frac{42}{111} \times 100=37.84 \%$