Answer:C) S, Cl, F shows the decreasing order of atomic radii across a period and down a group
Step-by-step explanation:
The Trend of atomic radius in a period occurs like this :
decreases from left to right as you go across a period. This is because of the shrinking of the nucleus as electrons are being added to the same orbital or shell conferring on the nucleus a positive charge as protons are also being added to the nucleus causing an attraction of the positively charged nucleus to electrons.
Increase down the group-This is because of the increasing energy levels caused by an increase in the number of shell causing a gap between outermost shell and the nucleus.
--Therefore On the same group, as you move across the period 3, Sulphur has a larger atomic radius than chlorine and on group 17 chlorine has a larger atomic radius than Fluorine.