MolSynapsequestion bank

MolSynapse / Question bank / Mole Concept / Empirical and molecular formula, percentage composition

JEE Main levelSingle correct optionDifficulty 2 of 3mc173

A hydrocarbon contains $92.3%$ carbon and $7.7%$ hydrogen by mass and its vapour density is $39$ . Its molecular formula is (C = 12, H = 1)

A $C X_{2} H X_{2}$
B $C X_{6} H X_{6}$
C $C X_{4} H X_{4}$
D $C X_{8} H X_{8}$

Answer: B

Mole ratio C : H = 7.69 : 7.70 = 1 : 1, so the empirical formula is CH (mass 13). Molar mass = 2 x 39 = 78. n = 78/13 = 6, so the formula is C6H6.

Practice Mole Concept More on Empirical and molecular formula, percentage composition

Previous questionNext question

More questions on Empirical and molecular formula, percentage composition