Which of the following hydroxides of group 2 elements is amphoteric ?

Options

A. `Mg(OH)_(2)`
B. `Ca(OH)_(2)`
C. `Be(OH)_(2)`
D. `Sr(OH)_(2)`

Answer

C

Explanation

the basic strength of metl hydroxides is decided by the ease with which they can release `OH^(-)` ions. As we move down the group the attraction between `M^(2+)` ion and `OH^(-)` ions decreases on account of the decrease of change density of `M^(2+)` ion. therefore, the basic strength of group 2 hydroxides increases on moving down the group. Group 2 hydroxides are less basic than the corresponding group 1 hydroxides bacause `M^(2+)` ios with greater charge density attract `OH^(-)` ions
Strongly in comparison to `M^(+)` ions of alkali metals. `Be(OH)_(2)` is insoluble in water but dissolves in acid as well as in solutions containing an excess of `OH^(-)` ions
`Be(OH)_(2)+2HCl toBeCl_(2)+2H_(2)O`
`Be(OH)_(2)+2NaOHtoNa_(2)BeO_(2).2H_(2)O` or `Na_(2)[Be(OH)_(4)]`
or `Be(OH)_(2)+2OH^(-)tounderset("Beryllate ion")([Be(OH)_(4)]^(2-))`
`Be(OH)_(2)` is therefore, amphoteric.