The stability of `+1` oxidation state among Al, Ga, In and Tl increases in the sequence :

Options

A. `Al lt Ga lt In lt Tl`
B. `Tl lt In lt Ga lt Al`
C. `In lt Tl lt Ga lt Al`
D. `Ga lt In lt Al lt Tl`

Answer

A

Explanation

As we move down the group from Al to Tl, inert pair effect becomes more and pronounced. In other words, stability of +1 oxidation state increases down the group , i.e., `Al lt Ga lt In lt Tl`.