question_answer 36)

    Which among the following elements has the largest atomic radii? (a) Na                                    (b) Mg                                  (c) K                                       (d) Ca

Answer:

                  (c) Na and K are in the same group and K is below than Ma, so K will have higher atomic radius i.e., K> 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> Ca. Also Na and Mg are in the same period, but Na belongs to 1 group and Mg belongs to2 group, so atomic radius of Na is more than Mg, i.e., Na> Mg. Thus, if we take all these together we get K > Na > Mg and K > Ca > Mg. Hence, we can say the atomic radius of K is largest.