D.U `=(2 xx 4 +2)/(2)=2^(@)`
D.U. means that is contains
a) Two (C=C) bond or
b) One (C-=C) bond or
c) One C=C bond and one cycloalkane or
d) two cyclic rings (bicyclo)
So, the possible structural, stereo and cyclic isomers of `C_(4)H_(6)` are as follows:
