Question

$200$ cc of a gas, measured at STP, has a mass of $0.268$ g. Molecular weight of the gas is:

• A. 16
• B. 2
• C. 28
• D. 30

Answer 1

The correct option is D 30

$200$ cc corresponds to $0.2$ L.

The mass of $0.2$ L at STP is $0.268$ g.

The mass of $22.4$ L at STP will be $\frac{22.4\times 0.268}{0.2}=30g$.

Since we know that 22.4 L corresponds to 1 mole of a gas.

Hence, the molecular weight of a gas is 30 gm.