To which class of compounds does ammonia belong?

Ammonia belongs to Inorganic compounds.

Inorganic compounds are those compounds which do not have C-H bond ( Carbon- Hydrogen bond). The molecular formula of ammonia is . It is also called as Nitrogen hydride. Nitrogen is linked to three hydrogen by the covalent bond. It exists in the gaseous form in its pure state.

Since there is no C-H bond in its molecular formula, therefore it belongs to inorganic compounds.