Chemistry · Periodicity of Elements and Periodic Properties

JEE Main 2025 — 28 January, Morning Shift — Question 41

Consider the following elements $\mathrm{In}, \mathrm{Tl}, \mathrm{Al}, \mathrm{Pb}, \mathrm{Sn}$ and Ge. The most stable oxidation states of elements with highest and lowest first ionisation enthalpies, respectively, are:

Option A:
(+2 and +3)
Option B:
(+4 and +3)
Option C:
(+4 and +1)
Correct
Option D:
(+1 and +4)

Answer: C

Step-by-step solution

Among the given elements, we have

$\mathrm{Ge}$ has the highest first ionisation enthalpy.

$\mathrm{Tl}$ has the lowest first ionisation enthalpy.

Most stable oxidation state of $\mathrm{Ge}$ is $+4$ .

Due to inert pair effect, $\mathrm{Tl}$ most commonly shows $+1$ oxidation state.

Therefore, the correct pair is $(+4\ \text{and}\ +1)$ .

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Exam: JEE Main 2025
Paper: 28 January, Morning Shift
Subject: Chemistry
Chapter: Periodicity of Elements and Periodic Properties
Topic: Valency, Diagonal Relationship, Inert Pair Effect & Other Miscellaneous Properties

The incorrect decreasing order of atomic radii is :

Answer: C

Step-by-step solution

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