# The number of $\pi-$bonds in ethane, ethene and ethyne are respectively

$\begin{array}{1 1}(a)\; 0,1,0&(b)\;0,1,2\\(c)\; 0,1,1&(d)\;0,2,3\end{array}$

In ethane$(C_2H_6)$ there is no $\pi-$bond, all are sigma bonds only, in ethane $(C_2H_4)$ there is only one $\pi-$bond and in ethyne $(C_2H_2)$ there are two $\pi-$bonds.
Hence (b) is the correct answer.
edited Apr 2, 2014