JEE Advanced · 2012 · 08 Apr 2012 · Paper 1 · Chemical Bonding and Molecular Structure

Allene has the structure ${\mathrm{H}}_2\mathrm{C}=\mathrm{C}={\mathrm{CH}}_2$. The central carbon atom forms two double bonds and has no lone pairs, requiring $sp$ hybridisation (linear geometry). The two terminal carbon atoms each form one double bond and two single bonds (to hydrogen), requiring $s{p}^2$ hybridisation. Therefore, the hybridisation types present are $sp$ (central carbon) and $s{p}^2$ (terminal carbons).