List two common ions that can form from elements in Group 7A.

Chlorine and Fluorine are the two common ions that can form from elements in Group 7A.

Explanation:

The elements in the periodic table can be classified depending upon the group number in which they are arranged. Group number is the column number given. So all the elements present in a single column of the specified number is said to belong to that group.

Similarly, in the present case, Group 7A is filled with highly electronegative elements. So they are also termed as halogens. As they are highly electronegative in nature, they can form ions easily. Among the five elements present in this group, the two most common elements which can easily form ions are Chlorine and Fluorine.