Exams › JEE Advanced › Chemistry

Arrange the following in the correct decreasing order of C-C bond length (C6H6 = benzene).

1. C2H6 > C2H4 > C6H6 > C2H2
2. C2H6 > C6H6 > C2H4 > C2H2
3. C2H4 > C2H6 > C2H2 > C6H6
4. C2H6 > C2H4 > C2H2 > C6H6

Correct answer: C2H6 > C6H6 > C2H4 > C2H2

Solution

Bond lengths: C2H6 single bond ~1.54 A; benzene ~1.39 A (bond order 1.5); C2H4 double bond ~1.34 A; C2H2 triple bond ~1.20 A. Higher bond order gives shorter, stronger bonds. So the order is C2H6 > C6H6 > C2H4 > C2H2.

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