The number of molecules and moles in 2.8375 litres of $\mathrm{O}_{2}$ at STP are respectively

(D) $7.527 \times 10^{22}$ and 0.125 mol

(A) $7.527 \times 10^{22}$ and 0.250 mol

(B) $1.505 \times 10^{23}$ and 0.250 mol

(C) $7.527 \times 10^{23}$ and 0.125 mol

JEE Main · 2023 · 10 Apr 2023 · Shift 1 · Some Basic Concepts of Chemistry

The number of molecules and moles in 2.8375 litres of

O_{2}

at STP are respectively

Answer: (D)

At standard temperature and pressure one mole of an ideal gas occupies 22.7 L on the currently recommended value. The amount of oxygen is therefore

n = \frac{2.8375}{22.7} = 0.125

mol. The number of molecules is this amount multiplied by the Avogadro constant,

0.125 \times 6.022 \times 1 0^{23} = 7.527 \times 1 0^{22}

. The sample thus contains

7.527 \times 1 0^{22}

molecules and 0.125 mol.

JEE Main · 2023 · 10 Apr 2023 · Shift 1 · Single correct option