Question

The moles of methane required to produce $81 g$ of water after complete combustion is ____ $\times 10^{-2}$ mol. [nearest integer]

Answer 1

$CH _{4}+2 O _{2} \rightarrow CO _{2}+2 H _{2} O$
POAC on $H$ atom
$ n _{ CH 4} \times 4= n _{ H 2 O } \times 2 $
$ n _{ CH _{4}}=\frac{81}{18} \times 2 \times \frac{1}{4}=\frac{81}{36} $
$ n _{ CH _{4}}=2.25 $
$=225 \times 10^{-2}$
Nearest Integers $=225$