No: Ammonium is a polyvalent cation that is not usually
considered either an acid or a base. Ammonium hydroxide is a base
that produces ammonium salts of the anions of an acid with which
the ammonium hydroxide reacts.
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When ammonium hydroxide decomposes, its ions are changed into
two compounds. These two compounds are the same that ammonium
hydroxide is formed from. Thus, ammonium hydroxide decomposes into
water and ammonia.
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Hydrochloric acid neutralises ammonium hydroxide to make
ammonium chloride.