JEE Main 2025 Jan 29 Shift 1, Chemistry Q23: Naming of Alkenes

The structure is $\mathrm{C}{\mathrm{H}}_2=\mathrm{CH}\text{-}\mathrm{CH}=\mathrm{CH}\text{-}\mathrm{C}\equiv \mathrm{CH}$ (six carbons; double bonds at C1-C2 and C3-C4; triple bond at C5-C6).

Count $\sigma$ bonds: 5 C-C $\sigma$ bonds along the backbone plus 6 C-H $\sigma$ bonds $=11\sigma$.

Count $\pi$ bonds: each $\mathrm{C}=\mathrm{C}$ contributes one $\pi$ (total 2) and the $\mathrm{C}\equiv \mathrm{C}$ contributes two $\pi$, giving $4\pi$.

$\sigma +\pi =11+4=15.$