JEE Main 2025 Apr 2 Shift 1, Chemistry Q14: Periodicity In Atomic Properties

JEE Main2025Apr 2, Shift 1Chemistry

Given below are two statements :

Statement (I) : The metallic radius of Al is less than that of Ga.

Statement (II) : The ionic radius of $A l^{3 +}$ is less than that of $G a^{3 +}$ .

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

A
Both Statement I and Statement II are incorrect
B
Statement I is incorrect but Statement II is correct
C
Statement I is correct but Statement II is incorrect
D
Both Statement I and Statement II are correct

Solution

In group 13, gallium sits immediately after the first-row transition series. The 3d electrons shield the nuclear charge poorly, so gallium's outer electrons feel a stronger effective nuclear charge and its metallic radius is actually smaller than aluminium's:

$B < G a < A l < I n < T l (metallic radius)$

Thus Statement I, which claims $r (A l) < r (G a)$ , is incorrect.

For the +3 ions, the cation radii follow the normal periodic trend down the group:

$B^{3 +} < A l^{3 +} < G a^{3 +} < I n^{3 +} < T l^{3 +}$

So $r (A l^{3 +}) < r (G a^{3 +})$ . Statement II is correct.

$∴$ Option (2) is correct.

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JEE Main 2025 Apr 2 Shift 1, Chemistry Q14: Periodicity In Atomic Properties

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