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Chemistry · Periodicity of Elements and Periodic Properties

JEE Main 2026 — 28 January, Morning Shift — Question 58

In period 4 of the periodic table, the elements with highest and lowest atomic radii are respectively.

  1. Option A:

    Na and Cl\mathrm{Na \ and \ Cl}

  2. Option B:

    K and Se\mathrm{K \ and \ Se}

  3. Option C:

    K and Br\mathrm{K \ and \ Br}

    Correct
  4. Option D:

    Rb and Br\mathrm{Rb \ and \ Br}

Answer: C

Step-by-step solution

Atomic radius decreases across a period from left to right due to increase in effective nuclear charge.

In period 4, K\mathrm{K} is the first element and has the highest atomic radius. Atomic radius decreases progressively towards Kr\mathrm{Kr}.

Among the given options, Br\mathrm{Br} is near the end of period 4 and has one of the lowest atomic radii.

Therefore the elements with highest and lowest atomic radii in period 4 are K and Br\mathrm{K \ and \ Br}

Hence, option C is correct.

Answer key and solution verified before publishing.

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Exam
JEE Main 2026
Paper
28 January, Morning Shift
Subject
Chemistry
Chapter
Periodicity of Elements and Periodic Properties
Topic
Periodicity in Physical Properties (shielding and sizes)
In period 4 of the periodic table, the elements with highest and… | JEE Main 2026 PYQ with Solution · DhiX AI