Which statement is true about a base when it reacts with another substance?
a. it receives a hydrogen ion.
b. it receives a hydroxide ion.
c. it donates a hydrogen ion.
d. it donates a hydroxide ion.

A. It receives a hydrogen ion.

Explanation:

The Bronsted lowry theory of acids and bases solves this problem. The theory states that;

Any compound that can transfer a proton to any other compound is an acid, and the compound that accepts the proton is a base. A proton is a nuclear particle with a unit positive electrical charge; it is represented by the symbol H+ because it constitutes the nucleus of a hydrogen atom.

So among the options, the option that says a base receives a hydrogen ion is the right answer which is option A.

Take the following reaction for example:

HCl  + NH₃    ⇌  NH₄⁺  +  Cl⁻

Hydrochloric acid (HCl) is the Brønsted-Lowry acid because it donates a hydrogen ion. Ammonia (NH3) is the Brønsted-Lowry base because it accepts the hydrogen ion.

2b2t

explanation:

2b2t