Question

The moles of methane required to produce 81 g of water after complete combustion is _____ × 10-2 mol. [nearest integer]

Answer 1

The correct answer is 225
$CH_4 + 2O_2 → CO_2 + 2H_2O$
1 mol $CH_4 →$ 2 mole $H_2O$
36 gm $H_2O →$ 1 mole $CH_4$
81 gm $H_2O → \frac{1}{36} ×$ 81 mole $CH_4$
→ 2.25 mole
→ 225 × 10-2