Question

The increasing order of atomic radii of the following group 13 elements is:

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

Hint:

Atomic radius decreases across a period due to the increasing nuclear charge, but there are exceptions in the d-block elements.

Answer 1

The Correct Option is B

In the periodic table, atomic radii generally increase down a group and decrease across a period. The elements Ga (Gallium) and Tl (Thallium) are exceptions due to the effect of d-block contraction. Therefore, the increasing order of atomic radii in Group 13 elements is: Ga < Al < In < Tl. Thus, the correct answer is Option (B).