Among the following, which atom is most likely to form an ion with a charge of 2+?

A. O B. AI C. Ca D. Na

C. Ca.

Explanation:

The atom loses or gains electrons forming anion or cation to reach stability (fill the outermost shell of the electron levels).

When atom gains electrons forms anions with negative charge.

While, when atom loses electrons forms cations with positive charge.

A. O:

O atom has 8 electrons in its nucleus and gains 2 electrons to reach stability (10 electrons, configuration of Ne).

So, it forms O²⁻.

B. AI:

Al atom has 13 electrons in its nucleus and loses 3 electrons to reach stability (10 electrons, configuration of Ne).

So, it forms Al³⁺.

C. Ca:

Ca atom has 12 electrons in its nucleus and loses 2 electrons to reach stability (10 electrons, configuration of Ne).

So, it forms Ca²⁺.

D. Na:

Na atom has 11 electrons in its nucleus and loses 1 electron to reach stability (10 electrons, configuration of Ne).

So, it forms Na⁺.