p-Block Elements (Group 13 & 14) · Question 15

Given below are two statements : In the light of the above statements, choose the most appropriate answer from the options given below :

1. Statement I is correct but Statement II is incorrect
2. Both Statement I and Statement II are correct
3. Statement I is incorrect but Statement II is correct
4. Both Statement I and Statement II are incorrect

Answer

(3) Statement I is incorrect but Statement II is correct

Solution

Statement I: As per NCERT, metallic radius of Al = 143 pm and of Ga = 135 pm.

In Ga the 10 d-electrons of the inner (3d) shell shield the nucleus poorly, so the effective nuclear charge rises and Ga is smaller than Al.

Metallic radius of Al is greater than that of Ga Statement I is incorrect.

Statement II: Ionic radius of Al3+ = 53.5 pm and of Ga3+ = 62 pm.

Al3+ is smaller than Ga3+ Statement II is correct.

Answer: (3)