Question

ammonia is a compound that forms hydroxide ions when it is dissolved in water; it is a

Explanation:

Ammonia ($NH_3$) accepts a proton from water when dissolved, producing hydroxide ions ($OH^-$) via the reaction: $NH_3 + H_2O
ightleftharpoons NH_4^+ + OH^-$. It does not contain $OH^-$ ions in its structure but generates them in solution, classifying it as a base.

Answer:

base