Correct Answer - Option 1 : Be(OH)
2
Concept:
For group- 2 metal hydroxides, basicity increases down the group, as:
Be(OH)2 < Mg(OH)2 < Ca(OH)2 < Sr(OH)2 < Ba(OH)2
This is because as the size of metal atom increases, M-OH bond length increases or M-OH bond become weaker thus readily breakes to release OH- ions which are responsible for the basicity of these solutions. But Be(OH)2 shows amphoteric (basic as well as acidic) character as it reacts with acid and alkali both which is shown in the following reactions,
Be(OH)2 as a base:
Be(OH)2 + 2HCl ⟶ BeCl2 + 2H2 O
Be(OH)2 as an acid:
Be(OH)2 + 2NaOH ⟶ Na2[Be(OH)4]
