Elements have been arranged in the following sequence on the basis of their increasing atomic masses. F, Na, Mg, Al, Si, P, S, Cl, Ar, K (a) Pick two sets of elements which have similar properties.
F and Cl are first and eighth element in the above sequence, therefore, they have similar properties. Please note that although Na and K have similar properties but they are not related as first and eighth element in the above sequence.
