JEE Main · 2026 · 28 Jan 2026 · Shift 2 · General Organic Chemistry

Hyperconjugation in a carbocation is measured by the number of C-H bonds on the carbons directly attached to the positive carbon ($\alpha$-hydrogens). In cation A the cationic carbon bears a methyl group (three $\alpha$-H), one ring $\mathrm{C}{\mathrm{H}}_2$ neighbour (two $\alpha$-H) and a ring neighbour carrying an ethyl group (one $\alpha$-H), giving six. In cation B the methyl-bearing cationic carbon has two ring $\mathrm{C}{\mathrm{H}}_2$ neighbours, giving $3+2+2=7$. In cation C the cationic carbon bears an ethyl group (two $\alpha$-H) and two ring $\mathrm{C}{\mathrm{H}}_2$ neighbours, giving $2+2+2=6$. In cation D the ethyl-bearing cationic carbon has one ring $\mathrm{C}{\mathrm{H}}_2$ neighbour and one ethyl-bearing ring neighbour, giving $2+2+1=5$. Cations A and C each have six $\alpha$-hydrogens, so these two share the same number of hyperconjugative interactions.