Question

How does the size of an anion compare with the size of its original (electrically neutral) atom?

A) The anion is larger than the original atom

B) The sizes are equal

C) The anion is smaller than the original atom

D) Anions of some atoms are larger, while others are smaller than the original atom

Answer 1

Neutral atoms can be turned into positively charged ions by removing one or more electrons. A neutral sodium atom, for example, contains 11 protons and 11 electrons. ... The gain or loss of electrons by an atom to form negative or positive ions has an enormous impact on the chemical and physical properties of the atom.

Answer 2

Remark

The anion will take on electrons. Something like Cl2 + 2e- ===> 2Cl- is an example.

If electrons are taken on, it is normally on the outside ring. That being the case the electrons have to spread out some to accommodate the additional electrons: the ion should increase in size and is larger than the parent atom.

The answer should be A.

B is wrong: they are not equal in size

C is wrong: The anion has to be larger to accommodate the  extra electrons.

D: If there are exceptions to A, I have no idea what they are. D is incorrect. I think you are intended to choose A.