Question

Given below are the pairs of group 13 elements showing their relation in terms of atomic radius. $(\mathrm{B}<\mathrm{Al}),(\mathrm{Al}<\mathrm{Ga}),(\mathrm{Ga}<\mathrm{In})$ and $(\mathrm{In}<\mathrm{Tl})$ Identify the elements present in the incorrect pair and in that pair find out the element (X) that has higher ionic radius $\left(\mathrm{M}^{3+}\right)$ than the other one. The atomic number of the element (X) is

• A. 31
• B. 49
• C. 13
• D. 81

Hint:

The atomic radius and ionic radius depend on the atomic number and the periodic trends.

Answer 1

The Correct Option is A

1. Incorrect pair: - $\mathrm{Al}<\mathrm{Ga}$
2. Ionic radius comparison: - $\mathrm{Al}^{3+}<\mathrm{Ga}^{3+}$ 
- The atomic number of $\mathrm{Ga}$ is 31. 
Therefore, the correct answer is (1) 31.