Question

The melting pt. of Group 13 follows the order
A. `B gt Al gt Ga gt In gt Tl`
B. `B gt Al lt Ga gt In gt Tl`
C. `B gt Al gt Tl gt In gt Ga`
D. `B gt Al lt GA lt In lt Tl`

Answer 1

Correct Answer - C
The expected order of decrease in melting points in `B gt Al gt Ga gt In gt Tl`. But this order is incorrect. Due to structure changes, melting point instead of decreasing increasing from Ga to Tl and as such Ga has the lowest melting point. Hence the actual order is `B gt Al gt Tl gt In gt Ga`.