Amphoteric hydroxides react with both alkalies with acids. Which of the following Group 2 metal hydroxides is soluble in sodium hydroxide?

1. Be(OH)2

2. Mg(OH)2

3. Ca(OH)2

4. Ba(OH)2



Hint: Beryllium oxide, and hydroxide are amphoteric in nature.

The solubility of hydroxides of alkaline earth metals increases from Be to Ba, in water. Be(OH)2 and Mg(OH)2 are almost insoluble.
Due to high hydration enthalpy and high lattice energy Be(OH)2 is not soluble in water. Be(OH)2 is an amphoteric hydroxide. With acids, Be(OH)2 is neutralized giving salts.
Be(OH)2 reacts with NaOH also forming beryllate.