Question

The molecular mass of $N{H}_3$ is ________.

• A. 18 u
• B. 10 u
• C. 17 u
• D. 16 u

Answer 1

The correct option is C 17 u

Molecular mass is equal to the sum of the masses of its constituent atoms.

Atomic mass of nitrogen = 14 u
Atomic mass of hydrogen = 1 u

$\therefore$ Molecular mass of $N{H}_3$
= atomic mass of nitrogen + 3 $\times$ atomic mass of hydrogen
= 14 + (3 $\times$1) = 14+3 = 17 u.