Number of amphoteric compounds among the following is ______
(A) BeO
(B) BaO
(C) $$BeOH_2$$
(D) $$Sr(OH)_2$$

We need to find how many of the given compounds are amphoteric.

An amphoteric compound is one that can react with both acids and bases.

(A) BeO — Beryllium oxide is amphoteric. It reacts with acids: $$BeO + 2HCl \to BeCl_2 + H_2O$$, and with bases: $$BeO + 2NaOH \to Na_2BeO_2 + H_2O$$.

(B) BaO — Barium oxide is a strongly basic oxide. It reacts with acids but not with bases. So it is not amphoteric.

(C) $$Be(OH)_2$$ — Beryllium hydroxide is amphoteric. It dissolves in both acids and bases: $$Be(OH)_2 + 2HCl \to BeCl_2 + 2H_2O$$ and $$Be(OH)_2 + 2NaOH \to Na_2[Be(OH)_4]$$.

(D) $$Sr(OH)_2$$ — Strontium hydroxide is a strong base. It is not amphoteric.

Among the alkaline earth metals, beryllium compounds show amphoteric behaviour due to the very small size and high polarising power of $$Be^{2+}$$. The oxides and hydroxides of Ba and Sr are strongly basic.

So, the number of amphoteric compounds is 2 (BeO and $$Be(OH)_2$$).

So, the answer is $$2$$.