JEE Main · 2022 · 26 Jun 2022 · Shift 2 · Some Basic Concepts of Chemistry

The moles of methane required to produce 81 g of water after complete combustion is

____

\times 1 0^{- 2}

mol. [nearest integer]

Answer: 225

Solution

The combustion reaction is:

CH_{4} + 2 O_{2} \to CO_{2} + 2 H_{2} O

.

From stoichiometry, 1 mole of

CH_{4}

produces 2 moles of

H_{2} O

.

Moles of water =

\frac{81}{18} = 4.5

mol.

Using POAC on H atoms:

n_{CH_{4}} \times 4 = n_{H_{2} O} \times 2

n_{CH_{4}} = \frac{4.5 \times 2}{4} = 2.25

mol

= 225 \times 1 0^{- 2}

mol.

Nearest integer: 225.

JEE Main · 2022 · 26 Jun 2022 · Shift 2 · Integer answer