Question

which is bigger in size na( 11 )or k(19) .why ?

Answer 1

K (19) is bigger in size because it has more number of electrons and its atomic size is big.
hope it helps u!!

Answer 2

potassium (19) is bigger in size as it goes down the group and the reason behind is sodium contains only three shells(2,8,1) whereas potassium contains 4 shells(2,8,8,1).

hope this answer helps..