Answer:
Explanation:
The reaction undergoing least change in volume will have lowest change in entropy .
1 ) C₂H₂(g) + 5/2O₂(g) → 2CO₂(g) + H₂O(g)
change in volume = 2.5 +1 - ( 2 + 1 ) = 0.5
2 ) CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(g)
change in volume = 2 +1 - ( 2 + 1 ) = zero
3 ) C₂H₆(g) + 7/2O₂(g) → 2CO₂(g) + 3H₂O(g)
change in volume = 3 +2 - ( 3.5 + 1 ) = 0.5
4 ) C₂H₄(g) + 3O₂(g) → 2CO₂(g) + 2H₂O(g)
change in volume = 2 +2 - ( 3 + 1 ) = zero
Hence least change in volume is in case no - 2 and 4 .
In reaction
C₂H₄(g) + 3O₂(g) → 2CO₂(g) + 2H₂O(g) and
CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(g)
∆S° or change in entropy is least .