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JEE Main 2026 Jan 21 Shift 2, Chemistry Q10: Periodicity In Atomic Properties

JEE Main2026Jan 21, Shift 2Chemistry
Q.

Given below are two statements:

Statement-I: The correct order in terms of atomic/ionic radii is Al > Mg > Mg > Al.

Statement-II: The correct order in terms of the magnitude of electron gain enthalpy is Cl > Br > S > O.

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

  1. A

    Both Statement I and Statement II are false

  2. B

    Statement I is false but Statement II is true

  3. C

    Statement I is true but Statement II is false

  4. D

    Both Statement I and Statement II are true

Solution

Statement I — the actual atomic-radius order across this period is Mg > Al (Al has a higher effective nuclear charge as you move right across period 3). So the correct order is Mg > Al > Mg > Al, not the one given. Statement I is false.

Statement II — Cl has the largest magnitude of among all elements; among halogens Cl > Br, and chlorine’s value also exceeds that of sulfur and oxygen (oxygen’s small size makes electron addition unfavourable due to repulsion). The order Cl > Br > S > O is correct. Statement II is true.

Concept behind this question

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