Assertion: According to kinetic theory of gases, all the collision between molecule-molecule, and between molecule-walls of container are perfectly elastic, so speed of each molecule in an isolated gaseous system remains constant. Reason: Distribution of speed among the molecules of gas does not change with time for the above system.

Step-by-step solution

The molecules of the gas or liquid are moving randomly, they are getting collide, in each collision, the momentum is getting a transfer from one molecule to another molecule, so the total energy of the system is constant but the molecular energy of the molecules is not constant, hence their velocity is also not a constant value. From the given graph, we can conclude that the ratio of the number of the molecules with certain velocity to the total number of molecules is constant. It is the cause of the conservation o