Q.2.37 P - Chemistry: Molecular Nature Of Matter And Change

Question

Choose the correct answer. The difference between the mass number of an isotope and its atomic number is (a)directly related to the identity of the element; (b) the number of electrons; (c) the number of neutrons; (d) the number of isotopes.

Step-by-Step Solution

Answer

The difference between the mass number of isotopes and their atomic number is the number of neutrons.

Step 1: Isotopes

The isotopes of an element are atoms that have different mass numbers due to a different number of neutrons.

Step2: Number of the neutrons in Isotopes:

Chlorine has two isotopes. ${}^{\mathbf{35}}\mathit{C}{\mathit{l}}_{\mathbf{17}}$and${}^{\mathbf{37}}\mathit{C}{\mathit{l}}_{\mathbf{17}}$

 Isotopes differ in the number of neutrons,  ${}^{\mathbf{35}}\mathit{C}{\mathit{l}}_{\mathbf{17}}$has  $\mathbf{35}\mathbf{-}\mathbf{17}\mathbf{=}\mathbf{18}$ neutrons whereas,${}^{\mathbf{37}}\mathit{C}{\mathit{l}}_{\mathbf{17}}$has $\mathbf{37}\mathbf{-}\mathbf{17}\mathbf{=}\mathbf{20}$neutrons .

 

Result: The correct option is (c) the number of neutrons.