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

The correct option is A $70$

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 $=70$