# The hybridisation of carbon atoms in $C-C$ single bond of $HC \equiv C-CH = CH_2$ is

$(a) \;sp^3-sp^3 \\ (b)\;sp^2-sp^3 \\ (c)\;sp-sp^2 \\ (d)\;sp^3-sp$

In $C \equiv C$ there is $SP$ hybridisation where as in $C=C$ it is $SP^2$ hybridisation.
So $sp-sp^2$
Hence c is the correct answer.