Question

In Victor Mayer's method, $0.2g$ of an organic substance displaced $56mL$ of air at STP, the molecular weight of the compound is :

• A. $56$
• B. $112$
• C. $80$
• D. $28$

Answer 1

The correct option is C $80$

Mass of the substance taken is $0.2g$.

Volume air displaced is $56mL$.

1 mole of a gas at STP $=22400mL$.

56 mL of air is displaced by 0.2 gm of an organic substance.

Therefore, 22400 mL of air is displaced by $=\frac{0.2g}{56}\times 22400=80gm$

Molecular weight of the compound = 80 gm.

Hence, option C is correct.