Which has the maximum electropositive character ?

Options

A. `Ba gt AI gt Ga gt In gt TI`
B. `B lt AI lt Ga lt In lt TI`
C. `B lt AI gt Ga lt In gt TI`
D. `B lt AI gt Ga gt In gt TI`

Answer

D

Explanation

As we move from B to AI, the sum of `Delta_(i) H_(1) + Delta_(i) H_(2) + Delta_(i) H_(3)` decreases substantially (6887 kJ `mol^(-1)` to 5137 kJ `mol^(-1)`)due to increase in the atomic size and hence AI has a high tendency to lose electrons. Since the electrode potentials increases from AI to TI therefore, their electropositive character decreases,
i.e., AI (-1.66 V) to Ga (-0.56 V) to In (-0.34 V) to TI (+ 1.26 V) accordingly.