Question

increaing order of Bond Length : C2H6,C2H4,C2H2

Answer 1

Bond length order follows : triple bond < double bond < single bond

The C—C bond order :
C2H2(120pm) < C2H4(134pm)< C2H6(154pm)

Answer 2

Bond length order:

Triple bond < Double bond < Single bond.

In general, increasing order of bond length is therefore,

C2H2 < C2H4 < C2H6.

C2h2, c2h4,c2h6 this is the correct increasing order based on the empirical formulae.

The bond order always based on  Triple bond < Double bond < Single bond.