The number of molecules in one litre of an ideal gas at 300 K and 2 atmospheric pressure with mean kinetic energy 2 $$\times$$ 10^$$-$$9 J per molecules is :

The relative permittivity of distilled water is 81. The velocity of light in it will be :

(Given $$\mu$$_r = 1)

List-I	List-II
(a) MI of the rod (length L, Mass M, about an axis $$ \bot $$ to the rod passing through the midpoint)	(i) $$8M{L^2}/3$$
(b) MI of the rod (length L, Mass 2M, about an axis $$ \bot $$ to the rod passing through one of its end)	(ii) $$M{L^2}/3$$
(c) MI of the rod (length 2L, Mass M, about an axis $$ \bot $$ to the rod passing through its midpoint)	(iii) $$M{L^2}/12$$
(d) MI of the rod (Length 2L, Mass 2M, about an axis $$ \bot $$ to the rod passing through one of its end)	(iv) $$2M{L^2}/3$$

Choose the correct answer from the options given below:

Three objects A, B and C are kept in a straight line on a frictionless horizontal surface. The masses of A, B and C are m, 2m and 2m respectively. A moves towards B with a speed of 9 m/s and makes an elastic collision with it. Thereafter B makes a completely inelastic collision with C. All motions occur along same straight line. The final speed of C is :