What is the most stable monatomic ion formed from iodine?

The most stable monoatomic ion formed will be

Explanation:

Monoatomic ion is defined as the ion which contains only one atom.

Iodine gas is the 53rd element of the periodic table having 53 electrons.

The electronic configuration of this element is:

This element will easily gain 1 electron to attain stable electronic configuration and hence will carry a negative charge.

The ion formed when iodine atom gains 1 electron is iodine ion and is written as .The ion formed is an anion.

Hence, the most stable monoatomic ion formed will be

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)