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

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

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

(A) Rb & Br

(B) Na & Cl

(C) K & Br

(D) K & Se

Correct Answer: (C)

Explanation

Across a period, atomic radius generally decreases from left to right due to increasing nuclear charge while the number of shells remains the same.

In period 4, potassium (K) is the first element and has the largest atomic radius because it has the lowest effective nuclear charge acting on its valence electron.

As we move across the period, atomic size decreases and among the elements listed, bromine (Br) has the smallest atomic radius in period 4.

Therefore, the elements with highest and lowest atomic radii in period 4 are K and Br respectively.

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