Question

An organic compound made of $C, H$ and $N$ contains $20\%$ nitrogen. Its molecular weight is :

• A. 70
• B. 140
• C. 100
• D. 65

Answer 1

Answer: (A)

70

Answer 2

Atomic mass of nitrogen $=14$
Since the compound contains $C , H$ and $N$, at least one $N$ atom must be there in the molecule.
$\because 20 \% N \equiv 14$
$\therefore 100 \% \equiv \frac{14}{20} \times 100=70$
$\therefore$ The minimum molecular weight of the organic compound $=70$.