Verified Solution • 2025–26 Session moderate

QJEEM23Ch2e71: JEE Main 2023 Chemistry - Class 11 JEEM23Ch2e71 Solution: The number of molecules and moles in 2.8375 litres of O at STP…

The number of molecules and moles in 2.8375 litres of O 2_2 at STP are respectively

Multiple Choice Options

  • A 1.505 ×\times 10 23^{23} and 0.250 mol
  • B 7.527 ×\times 10 22^{22} and 0.250 mol
  • C 7.527 ×\times 10 23^{23} and 0.125 mol
  • D 7.527 ×\times 10 22^{22} and 0.125 mol

Step-by-Step Verified Solution

At STP, one mole of any gas occupies 22.4 liters. Therefore, 2.8375 liters of oxygen gas at STP is equal to 0.125 moles. The number of molecules of oxygen gas in 0.125 moles is calculated by multiplying the number of moles by Avogadro's number, which is 6.022×10236.022 × 10^{23} molecules/mol. This gives us a total of 7.527×10227.527 × 10^{22} molecules of oxygen gas in 2.8375 liters at STP.

Here is the calculation:

\begin{align}&\text{Number of moles of }O_2 = \frac{2.8375 \text{ L}}{22.4 \text{ L/mol}} = 0.125 \text{ mol} \\\\&\text{Number of molecules of }O_2 = 0.125 \text{ mol} \times 6.022 \times 10^{23} \text{ molecules/mol} = 7.527 \times 10^{22} \text{ molecules}\end{align}

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