Question

The correct order of increasing atomic radii among the elements $B,Al$ and $Ga$ is:

• A. B < Al < Ga
• B. Ga < Al < B
• C. B < Ga < Al
• D. Al < Ga < B

Answer 1

The correct option is C B < Ga < Al

Atomic radii of elements increase from top to bottom in the group. This is due to the increase in the number of energy shells in each succeeding element. However, the atomic radii of Gallium (Ga) is less than that of aluminium (Al) because of poor screening effect of electrons in the d-orbital. Therefore, the correct order of increasing atomic radii will be: B < Ga < Al