According to Baeyer's strain theory:- 

Stability of cycloalkane is inversely proportional to the angle of strain $\left(\text{θ}\right)$  means a greater angle of strain lesser stability of cycloalkane (till cyclohexane).

Stability order of cycloalkane: 

${\text{C}}_3{\text{H}}_6<{\text{C}}_4{\text{H}}_8 <{\text{C}}_5{\text{H}}_{10} <{\text{C}}_6{\text{H}}_{12} \left( \text{Minimum} \text{θ}\right)\text{}$