The molecular mass of methane  is $16 \mathrm{g}/\mathrm{mol}$.

The reaction is as follows,

${\mathrm{CH}}_4+2{\mathrm{O}}_2\to {\mathrm{CO}}_2+2{\mathrm{H}}_2\mathrm{O}$

Moles of ${\mathrm{CO}}_2=\frac{\text{mass}}{\text{molar mass}}=\frac{22}{44}=0.5$

So, required moles of ${\mathrm{CH}}_4=0.5$

$$\begin{gathered} {\text{ Mass of CH}}_{\text{4}}=0.5\times 16 \\ =8 \mathrm{gm} \end{gathered}$$