How many molecules are present in $22400 \mathrm{~cm}^3$ of a gas at STP?

How many molecules are present in $22400 \mathrm{~cm}^3$ of a gas at STP?
  1. $22.4 \times 10^{20}$
  2. $6.022 \times 10^{23}$
  3. $6.022 \times 10^{20}$
  4. $22.4 \times 10^{23}$

Solution

$\begin{aligned} & \text { Number of moles of gas }=\frac{\text { Volume }}{22.4 \mathrm{~L}}\left[22400 \mathrm{~cm}^3=22.4 \mathrm{~L}\right] \\ & \quad=\frac{22.4}{22.4}=1 \\ & \text { Number of molecules }=\text { moles } \times \mathrm{N}_{\mathrm{A}} \\ & =6.022 \times 10^{23}\end{aligned}$

Asked in: MHT CET 2021 (23 Sep Shift 1)

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