NH3 (Ammonia) is not an alkali. Alkalis are typically defined as bases that are soluble in water and have a pH greater than 7. They are often composed of metal hydroxides, such as NaOH (Sodium Hydroxide) and Ca(OH)2 (Calcium Hydroxide).
Ammonia, on the other hand, is a compound made of nitrogen and hydrogen and is a weak base. It does not have the properties of an alkali as it does not have a pH greater than 7 and is not soluble in water.