Question

Which among the following elements has the largest atomic radii?

• A. $\mathrm{Na}$
• B. $\mathrm{Mg}$
• C. $\mathrm{K}$
• D. $\mathrm{Ca}$

Answer 1

The correct option is C

$\mathrm{K}$

The explanation for correct option

(C)$\mathrm{K}$

Atomic radii

• In general, the atomic radii decrease on going left to right in a period.
• It's because the outer electrons are in the same valence shell during the period, and the effective nuclear charge rises as the atomic number rises, increasing the attraction of electrons to the nucleus.
• In general, the atomic radii increase going top to bottom in the group with the increase in atomic number.
• The given elements are arranged in the periodic table as follows:-

• So, the order of atomic radii is as follows:-
• $\mathrm{Mg}<\mathrm{Ca}<\mathrm{Na}<\mathrm{K}$
• So, potassium has the largest atomic radii among the given elements.

Hence, option (C) is correct. Potassium has the largest atomic radii.