The number of molecules in 22 grams of  ${\text{CO}}_2$ are

$\begin{array}{l}1{\text{\hspace{0.17em}mole\hspace{0.17em}CO}}_2\to 44{\text{\hspace{0.17em}g\hspace{0.17em}CO}}_2\to {\text{N\hspace{0.17em}molecules\hspace{0.17em}of\hspace{0.17em}CO}}_2\\ 22{\text{\hspace{0.17em}g\hspace{0.17em}CO}}_{\text{2}}\to x{\text{\hspace{0.17em}molecules\hspace{0.17em}of\hspace{0.17em}CO}}_2\\ x=\frac{22\times \text{N}}{44}\\ x=\frac{\text{N}}{2}moleculesofC{O}_2\end{array}$