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SSC CHSL 2023 PYQ — Question 30

SSC CHSL - 11 Aug 2023 - Shift 1 • General Awareness • Q30

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The correct order of electron affinity of halogens is:

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Correct answer: C

Explanation

The correct answer is option 3 i.e. Cl > F > Br > I.

  1. Chlorine (Cl) has the highest electron affinity among halogens due to its optimal size, balancing nuclear attraction and electron-electron repulsion.

  2. Fluorine (F) has lower electron affinity than Cl because its small size leads to high electron-electron repulsion in the compact 2p subshell.

  3. Bromine (Br) follows, as electron affinity decreases down the group due to increasing atomic size.

  4. Iodine (I) has the lowest electron affinity in this series because of its large atomic radius and weaker nuclear attraction for incoming electrons.

Why not others?

  • F > Cl > Br > I is incorrect because F’s EA is lower than Cl’s due to repulsion in the small 2p orbital.

  • Br > Cl > I > F or similar permutations violate the observed trend.

Key Point: While electron affinity generally decreases down the group, the anomaly between F and Cl makes Cl > F