Amphoteric Hydroxide:
An amphoteric hydroxide is a substance that can act as both an acid and a base. It can react with both acidic and basic solutions to form salts.

Possible Options:
1. Ca(OH)2 (Calcium hydroxide)
2. Be(OH)2 (Beryllium hydroxide)
3. Sr(OH)2 (Strontium hydroxide)
4. Mg(OH)2 (Magnesium hydroxide)

Explanation:
Out of the given options, the amphoteric hydroxide is Mg(OH)2 (Magnesium hydroxide). It shows amphoteric behavior and reacts with both acids and bases to form salts.

When Mg(OH)2 reacts with acids, it forms magnesium salts. For example, with hydrochloric acid (HCl), it forms magnesium chloride (MgCl2).

Mg(OH)2 + 2HCl → MgCl2 + 2H2O

Similarly, when Mg(OH)2 reacts with bases, it forms magnesium salts. For example, with sodium hydroxide (NaOH), it forms magnesium hydroxide (Mg(OH)2).

Mg(OH)2 + 2NaOH → Mg(OH)2 + 2NaCl

Therefore, Mg(OH)2 is an example of an amphoteric hydroxide.

Conclusion:
The correct option for the given question is Mg(OH)2 (Magnesium hydroxide) as it shows amphoteric behavior and reacts with both acids and bases to form salts.

Oxides nd hydroxides of S block are basic in nature but Be is an exception it's hydroxides nd oxides are Amphoteric in nature.Hence, option 2 is correct.