mass of $CO _{2}( g )=330\, g$

mass of $H _{2} O (\ell)=270\, g$

mass of carbon $= n _{ CO _{2}} \times 12$

$=\frac{330}{44} \times 12=90 \,g$

$\,\%$ of carbon $=\frac{90}{120} \times 100=75 \,\%$

mass of hydrogen $= n _{ H _{2} O } \times 2$

$=\frac{270}{18} \times 2=30 \,g$

$\,\%$ of hydrogen $=\frac{30}{120} \times 100=25 \,\%$