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

Soln:

Answer is (c) K Soln:

K has largest atomic radii because atomic radii decreases from left to right along a period. This is because of increase in nuclear charge which tends to pull the electron closer to the nucleus and reduces the size of the atom. Hence K has the largest atomic radii.