Question

The number of atoms in 4.25 g of NH₃ is approximately _______.

(A) 1 x 10²³ 

(B) 2 x 10²³ 

(C) 4 x 10²³ 

(D) 6 x 10²³

Answer 1

Correct option: (D) 6 x 10²³

Molecular mass of NH₃ = 14 + (3 x 1) = 17

Number of moles = \(\cfrac{4.25}{17}\) = 0.25

Number of molecules of NH₃ = 0.25 x N_A

= 1.506 x 10²³ molecules

One molecule of NH₃ contains 4 atoms.

∴ 1.506 x 10²³ molecules will contain

= 1.506 x 10²³ x 4

= 6.023 x 10²³ atoms ≈ 6 x 10²³ atoms.