Which group/family contains elements with the smallest radius within the same period?

Halogens

Explanation:

From the given choices, the halogens will have the smallest radius within the same period.

The size of an atom is estimated by the atomic radius. This is taken as half of the inter-nuclear distance between two covalently bonded atoms of non-metallic elements or half of the distance between two nuclei in the solid state.

Across a period in the periodic table, atomic radii decrease progressively from left to right. Down a group from top to bottom, atomic radii increase progressively due to the addition of successive shells.

Since halogen is the right most group from the choices given, it will have the smallest radius.

In any atom of any element, you will find protons and neutrons in the nucleus of any atom 

Ibelieve it's temperature! i'm not 100% sure.