Question

Which of the following has maximum numbers of atoms?

A. 18 g of H₂O

B. 18 g of O₂

C. 18 g of CO₂

D. 18 g of CH₄

Answer 1

When the mass is same, the number of atoms is inversely proportional to the molecular mass. This means less will be the molecular mass, more will be the number of atoms.

H₂O = 2× 1 + 16 = 18u

O₂ = 2× 16 = 32u

CO₂ = 12 × 2 × 16 = 44u

CH₄ = 12 + 4× 1 = 16u

Hence, 18 g of CH₄ has maximum numbers of atoms.