4.4 g of CO₂ and 2.24 litre of H₂ at STP are mixed in a container. The total number of molecules present in the container will be:

$$\begin{gathered} \mathrm{No}.\mathrm{of} \mathrm{moles} \mathrm{of} {\mathrm{CO}}_2=\frac{4.4}{44} \\ \mathrm{No}.\mathrm{of} \mathrm{moles} \mathrm{of} {\mathrm{H}}_2=\frac{2.24}{22.4} \end{gathered}$$

Total no. of moles $=\frac{4.4}{44}+\frac{2.24}{22.4}=\frac{1}{5}$

No.of molecules $=\frac{\mathrm{N}}{5}=\frac{6.023\times {10}^{23}}{5}=1.2044\times {10}^{23}$