Question

Which of the following contains the highest number of atoms?

Options

• 7 g of N₂

• 2 g of H₂

• 4.25 g of ammonia

• 23 g of sodium

Answer 1

2 g of H₂

Explanation:

Total number of atoms in a molecule = n × N_A × Number of atoms in a formula

∴ Total number of atoms in 7 g of N₂

= `7/28 xx "N"_"A" xx 2`

= `1/2 "N"_"A"`

Total number of atoms in 2 g of H₂

= `2/2 xx "N"_"A" xx 2`

= 2 N_A

Total number of atoms in 4.25 g of NH₃

= `4.25/17 xx "N"_"A" xx 4`

= N_A

Total number of atoms in 23 g of sodium

= `23/23 xx "N"_"A" xx 1`

= N_A

Thus, the highest number of atoms is present in 2 g of hydrogen.