Question

In allene structure, three carbon atoms are joined by :

• A. three $\sigma$- and three $\pi$-bond
• B. two $\sigma$- and one $\pi$-bond
• C. two $\sigma$- and two $\pi$ - bonds
• D. three $\pi$- bonds only

Answer 1

Answer: (C)

two $\sigma$- and two $\pi$ - bonds

Allene is $C{H}_2=C=C{H}_2$.
The terminal carbons each form one $\sigma$ with the central carbon. The other bond formed by the terminal carbon with the central carbon is a $\pi$ bond. Hence in total there are two $\sigma$- and two $\pi$ - bonds.