${\mathrm{CH}}_4\left(\mathrm{g}\right)+2{\mathrm{O}}_2\left(\mathrm{g}\right)⟶{\mathrm{CO}}_2\left(\mathrm{g}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)$

How many moles of methane are required to produce 22 g ${\mathrm{CO}}_2\left(\mathrm{g}\right)$ after combustion?

According to the chemical equation

${\mathrm{CH}}_4\left(\mathrm{g}\right)+2{\mathrm{O}}_2\left(\mathrm{g}\right)⟶{\mathrm{CO}}_2\left(\mathrm{g}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)$

$44 {\mathrm{gCO}}_2\left(\mathrm{g}\right)\text{ is obtained from }16 {\mathrm{gCH}}_4\left(\mathrm{g}\right)$

$\left[\because 1\text{ mole }{\mathrm{CO}}_2\left(\mathrm{g}\right)\text{ is obtained from }1\text{ mole of }{\mathrm{CH}}_4\left(\mathrm{g}\right)\right]$

$\text{ Mole of }{\mathrm{CO}}_2\left(\mathrm{g}\right)=\frac{22 {\mathrm{gCO}}_2\left(\mathrm{g}\right)}{44 {\mathrm{gCO}}_2\left(\mathrm{g}\right)}$

                         = $0.5\text{ mole }{\mathrm{CO}}_2\left(\mathrm{g}\right)$

$\text{ Hence, }0.5\text{ mole }{\mathrm{CO}}_2\left(\mathrm{g}\right)\text{ would be obtained from }0.5\text{ mole }$${\mathrm{CH}}_4\left(\mathrm{g}\right)\text{ or }0.5\text{ mole of }{\mathrm{CH}}_4\left(\mathrm{g}\right)\text{ would be required to }$$\text{ produce }22 {\mathrm{gCO}}_2\left(\mathrm{g}\right)\text{. }$