Which of the following contain the same number of atoms

Question

Which of the following contain the same number of atoms?

(Given: Molar mass in g ${mol}^{- 1}$ of H, He, O and S are 1, 4, 16 and 32 respectively)

A. 2 g of $O_{2}$ gas

B. 4 g of ${SO}_{2}$ 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: [2026]

Smart Achievers · Accepted Answer

(4)

Substance	Moles of substance (given mass/molar mass)	Number of molecules	Atoms = Atomicity × number of molecules
(A) 2 g of $O_{2}$ gas	$\frac{2}{32} = \frac{1}{16}$	$\frac{1}{16} N_{A}$	$2 \times \frac{1}{16} N_{A} = \frac{1}{8} N_{A} = 0.125 N_{A}$
(B) 4 g of ${SO}_{2}$ gas	$\frac{4}{64} = \frac{1}{16}$	$\frac{1}{16} N_{A}$	$3 \times \frac{1}{16} N_{A} = 0.1875 N_{A}$
(E) $H_{2}$ gas	$0.0625$	$0.0625 N_{A}$	$2 \times 0.0625 N_{A} = 0.125 N_{A}$

Volume of gas at STP	Moles of substance (Vol in L / 22.4)	Number of molecules	Atoms = Atomicity × number of molecules
(C) 1400 mL (1.4 L) of $O_{2}$ gas	$\frac{1.4}{22.4} = \frac{1}{16}$	$\frac{1}{16} N_{A}$	$2 \times \frac{1}{16} N_{A} = \frac{1}{8} N_{A} = 0.125 N_{A}$
(E) 0.05 L of He gas	$\frac{0.05}{22.4} = \frac{1}{448}$	$2 \times \frac{1}{16} N_{A} = \frac{1}{8} N_{A}$	$\frac{1}{448} N_{A} = 0.00223 N_{A}$

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