Question

The atoms of which element will gain electrons to form an ion?
oxygen
calcium
lithium
mercury

Answer 1

Explanation:

Oxygen will gain electrons to form ion (O²⁻).

Calcium loses electron to form ion (Ca²⁺)

Lithium loses electron to form ion (Li⁺)

Mercury loses electron to form ion (Hg²⁺)

Here it is stated in question that the element will gain electron it means electron bears negative charge.

Therefore,

Option A is correct ✔.