The most strained cycloalkane is
- cyclopropane
- cyclobutane
- cyclopentane
- cyclohexane
Solution
The intense angle strain leads to nonlinear orbital overlap of its $\mathrm{sp}^{3}$ orbitals.
Because of the bond's instability, cyclopropane is more reactive than other alkanes. Since any three points make a plane and cyclopropane has only three carbons, cyclopropane is planar.
The $\mathrm{H-C-H }$ bond angle is $115^{\circ}$ whereas $106^{\circ}$ is expected as in the $\mathrm{CH}_{2}$ groups of propane.
Asked in: JEE-TOPICTESTS-CHEMISTRY