Question

Two flasks $A$ and $B$ is $500mL$ each are respectively filled with $O_2$ and $S{O}_2$ at $300K$ and $1atm$ pressure. The flasks contain :

• A. The same number of atoms
• B. The same number of molecules
• C. More number of moles in flask $A$ as compared to flask $B$
• D. The same amount of gases

Answer 1

The correct option is B The same number of molecules

Assumption: Ideal gas law holds for both gases.

Since pressure, temperature and volume are the same for both the gases and $PV=nRT$

$\to$ $n$ is same for both the gases

Thus both gases have the same no. of moles.
Or both have the same number of molecules.

No. of atoms in 1 molecule of $O_2$=2
No. of atoms in 1 molecule of $S{O}_2$=3

Thus no. of atoms in these gases are in the ratio 2:3 (hence not same no. of atoms.)
Thus (b) is the correct answer.