Which of the following contain the same number of atoms? (Given : Molar mass in \(\mathrm{g} \mathrm{mol}^{-1}\) of \(\mathrm{H}, \mathrm{He}, \mathrm{O}\) and S are \(1,4,16\) and 32 respectively) A. 2 g of \(\mathrm{O}_{2}\) gas B. 4 g fo \(\mathrm{SO}_{2}\) gas C. 1400 mL of \(\mathrm{O}_{2}\) at STP D. 0.05 L of He at STP E, 0.0625 mol of \(\mathrm{H}_{2}\) gas Choose the correct answer from the options given below :

JEE Main · 2026 · 06 Apr 2026 · Shift 2 · Some Basic Concepts of Chemistry

Which of the following contain the same number of atoms?
(Given : Molar mass in

g mol^{- 1}

H, He, O

and S are

1, 4, 16

and 32 respectively)
A. 2 g of

O_{2}

gas
B. 4 g fo

SO_{2}

gas
C. 1400 mL of

O_{2}

at STP
D. 0.05 L of He at STP
E, 0.0625 mol of

H_{2}

gas
Choose the correct answer from the options given below :

Answer: (D)

The number of atoms equals the moles of substance times the atoms per formula unit times

N_{A}

. For 2 g of

O_{2}

\frac{2}{32} \times 2 = 0.125 N_{A}

. For 4 g of

S O_{2}

\frac{4}{64} \times 3 = 0.1875 N_{A}

. For 1400 mL of

O_{2}

at STP:

\frac{1.4}{22.4} \times 2 = 0.125 N_{A}

. For 0.05 L of He at STP:

\frac{0.05}{22.4} \times 1 = 2.2 \times 1 0^{- 3} N_{A}

. For 0.0625 mol of

H_{2}

0.0625 \times 2 = 0.125 N_{A}

. The samples 2 g

O_{2}

, 1400 mL

O_{2}

at STP and 0.0625 mol

H_{2}

each hold

0.125 N_{A}

atoms, so these three contain the same number of atoms.

JEE Main · 2026 · 06 Apr 2026 · Shift 2 · Single correct option