Question

Which of the following is an amphoteric hydroxide?

• A. \(Sr(OH)_2\)
• B. \(Ca(OH)_2\)
• C. \(Mg(OH)_2\)
• D. \(Be(OH)_2\)

Answer 1

The Correct Option is D

To determine which of the given hydroxides is amphoteric, let's first understand the concept of amphoteric substances. An amphoteric compound is one that can act as both an acid and a base. In the case of hydroxides, amphoteric hydroxides can react with both acids and bases to form salts and water.

Let's analyze each option provided:

1. Sr(OH)_2: Strontium hydroxide is a strong base and does not exhibit amphoteric behavior. It primarily acts as a base.
2. Ca(OH)_2: Calcium hydroxide is also a strong base and does not exhibit amphoteric properties. It reacts with acids but usually not with bases.
3. Mg(OH)_2: Magnesium hydroxide is a weak base. It has very limited amphoteric tendencies and is mostly basic in nature.
4. Be(OH)_2: Beryllium hydroxide is amphoteric. It can react with acids to form beryllium salts and with bases to form beryllate complexes.

The correct answer is Be(OH)_2, as it exhibits clear amphoteric behavior. It can react both with acidic solutions and basic solutions:

• With acids, it forms salts: Be(OH)_2 + 2HCl \rightarrow BeCl_2 + 2H_2O
• With bases, it forms beryllate ions: Be(OH)_2 + 2OH^- \rightarrow [Be(OH)_4]^{2-}

Hence, the amphoteric hydroxide among the options given is Be(OH)_2.