Question

The isotopes of Hydrogen H are ${}_{\text{1}}^{\text{1}}\text{H},{}_{\text{1}}^{\text{2}}\text{H}$ and ${}_{\text{1}}^{\text{3}}\text{H}$ respectively. What is the ratio of number of nucleons in these respective isotopes?

• A. 1 : 2 : 3
• B. 1 : 1 : 1
• C. 2 : 1 : 3
• D. 3 : 2 : 1

Answer 1

The correct option is A 1 : 2 : 3

- Nucleons are the particles that make up the nucleus of an atom i.e. neutrons and protons.

- Mass number of an element is the sum of number of protons and number of neutrons present in the nucleus.

- Mass number of ${}_{\text{1}}^{\text{1}}\text{H},{}_{\text{1}}^{\text{2}}\text{H}$ and ${}_{\text{1}}^{\text{3}}\text{H}$ are 1, 2, 3 respectively.

- Ratio of nucleons = ratio of mass number.
Therefore, the ratio of nucleons is
$\text{1 : 2 : 3}$