Assertion : At critical point the densities of substance in gaseous and liquid states are same. Reason : Critical temperature is the temperature at which the real gas exhibit ideal behaviour for considerable range of pressure.

Step-by-step solution

Temperature at which the real gas exhibit ideal behaviour for considerable range of pressure is known as Boyle's temperature. T_b= a b R a , and b are van der Waal's constant. Critical temperature is the temperature above which the gas cannot be liquefied, how so ever high pressure may be applied : T_c= 8 a 27 R b .