Which among the following elements has the largest atomic radii ?

Options

A. Na
B. Mg
C. K
D. Ca

Answer

C

Explanation

Na and K are in the same group and K is below than Na, so K will have higher atomic radius i.e., `K gt Na`. In a period on moving from left to right, atomic radius decreases. Since, K and Ca are in the same period and K is in 1 group and Ca is in 2 group, so atomic radius of K will be more than Ca, i.e., `K gt Ca`
Also Na and Mg are in the same period, but Na belongs to 1 group and Mg belongs to 2 group, so atomic radius of Na is more than Mg, i.e., `Na gt Mg`. Thus, if we take all these together we get `K gt Na gt Mg and K gt Ca gt Mg`. Hence, we can say the atomic radius of K is largest.