Q. Assertion (A) Cyclohexane is the most stable cycloalkane.
Reason (R) Cyclopropane and cyclobutane are less stable due to angle strain and torsional strain.
The correct answer is

 1966  242 EAMCETEAMCET 2011 Report Error

Solution:

In cycloalkane the heat of combustion of cyclohexane is the lowest hence it is the most stable cycloalkane. Cyclopropane and cyclobutane are less stable due to angle strain and torsional strain, therefore cyclopropane and cyclobutane are reactive cycloalkane.