On complete combustion 1.0 g of an organic compound (X) gave 1.46 g of $\mathrm{CO}_{2}$ and 0.567 g of $\mathrm{H}_{2} \mathrm{O}$. The empirical formula mass of compound (X) is ______ g. (Given molar mass in $\mathrm{g} \mathrm{mol}^{-1} \mathrm{C}: 12, \mathrm{H}: 1, \mathrm{O}: 16$ )

JEE Main · 2025 · 02 Apr 2025 · Shift 1 · Some Basic Concepts of Chemistry

On complete combustion 1.0 g of an organic compound (X) gave 1.46 g of

CO_{2}

and 0.567 g of

H_{2} O

. The empirical formula mass of compound (X) is ______ g.
(Given molar mass in

g mol^{- 1} C : 12, H : 1, O : 16

)

Answer: (A)

The carbon comes from the carbon dioxide,

1.46/44 = 0.0332

mol weighing

0.398 g

. The hydrogen comes from the water,

2 \times 0.567/18 = 0.063

mol weighing

0.063 g

. The remaining mass,

1.0 - 0.398 - 0.063 = 0.539 g

, is oxygen, giving

0.539/16 = 0.0337

mol. The mole ratio of carbon to hydrogen to oxygen is

0.0332 : 0.063 : 0.0337

, close to

1 : 2 : 1

, so the empirical formula is

CH X_{2} O

and its formula mass is

12 + 2 + 16 = 30 g

JEE Main · 2025 · 02 Apr 2025 · Shift 1 · Single correct option