Q30 / 90 · JEE Main 2022 (26 Jun Shift 2) · Chemistry

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

Correct answer: 225

Solution

${CH}_{4} + 2 O_{2} ⟶ {CO}_{2} + 2 H_{2} O$

POAC on H atom

${nCH}_{4} \times 4 = {nH}_{2} O \times 2$

${nCH}_{4} = \frac{81}{18} \times 2 \times \frac{1}{4} = \frac{81}{36}$

${nCH}_{4} = 2.25$

$= 225 \times 10^{- 2}$

Hence, the number of moles of methane is $225 \times 10^{- 2}$

Hence, the correct answer is 225.