With reference to the halogen family of elements, consider the following:
1. The halogen that is most active chemically
2. The halogen with the smallest ionic radius
3. The halogen that first shows some visible metallic properties at room temperature
Which among the following is the correct set of elements denoting the above properties respectively:

Answer: [C] Fluorine, Fluorine, Iodine

In the halogen family, the most active nonmetal would be the top element, fluorine, because it has the highest electronegativity. As you proceed down a group, the ionic radius increases as additional energy levels are filled farther from the nucleus. Therefore fluorine, the top element, has the smallest ionic radius. Some physical characteristics of metal are found in iodine, the fourth halogen down in the group.

This question is a part of GKToday's Integrated IAS General Studies Module