The average translational energy and the rms speed of the molecules in a sample of oxygen gas at 300 K are 6.21 x 10-21 J and 484 m/s respectively. Assuming ideal gas behaviour, the corresponding values at 600 K are nearly
(a) 12.42 x 10-21 J, 968 m/s
(b) 8.78 x 10-21 J, 684 m/s
(c) 6.21 x 10-21 J, 968 m/s
(d) 12.42 x 10-21 J, 684 m/s