NCERT Solutions for Class 11 Physics Ch-12: Kinetic Theory

Answer: Two basic postulates are: (i) A gas consists of a very large number of tiny molecules in constant, random motion, colliding elastically with each other and with the walls of the container; (ii) The molecules are treated as point masses, and the volume occupied by the molecules themselves is negligible compared to the volume of the container.

Answer: The ideal gas equation is PV = nRT, where P is the pressure, V is the volume, n is the number of moles of the gas, R is the universal gas constant, and T is the absolute temperature of the gas.

Answer: According to kinetic theory, the absolute temperature of a gas is directly proportional to the average kinetic energy of translation of its molecules; specifically, the average kinetic energy per molecule is given by (3/2)kBT, where kB is the Boltzmann constant.

Answer: The degrees of freedom of a molecule refer to the total number of independent ways in which it can possess energy, such as through translational, rotational, or vibrational motion. A monatomic gas molecule has 3 degrees of freedom (translational only), while a diatomic gas molecule typically has 5 (3 translational and 2 rotational).

Answer: The law of equipartition of energy states that in thermal equilibrium, the total energy of a system is equally distributed among all its degrees of freedom, with each degree of freedom contributing an average energy of (1/2)kBT per molecule.