Question

which gas condensed first and why......?

Answer 1

Because boiling point and condensing point are the same thing, they just occur in different directions. As the temperature of a mixture of gases is reduced, the ones which condense first are those with the higher condensing (boiling) point, which were the last to boil/evaporate as the temperature was increased.

Answer 2

The gas with higher boiling point will condense at the beginning....