Stability of monovalent and trivalent cations of `Ga,In, Tl` lie in following sequence :

Options

A. `Ga^(3+) lt In^(3+) gt Tl^(3+)`
B. `Ga^(3+) gt In^(3+) gt Tl^(3+)`
C. `Tl^(oplus) gt In^(oplus) gt Ga^(oplus)`
D. `Ga^(oplus) lt In^(oplus) gt Tl^(oplus)`

Answer

B, C

Explanation

Among `13` group elements, due to the inert pair effect, stability of higher oxidation state, i.e. `+3` decreases down the group `(darr)` and stability of lower oxidation state, i.e. `+1`, increases down the group `(darr)`.