The average translational K.E. of the molecules in a sample of oxygen at 300K is 6 x 10-20. What is the average translational energy at 750 K?

2 x 10^-19 J

1.5 x 10^-19 J

3.5 x 10^-18 J

3.5 x 10^-21 J

The average translational kinetic energy of molecules is directly proportional to the temperature (in Kelvin).

Since the temperature is increased from 300 K to 750 K, the average translational kinetic energy will also increase by a factor of 750/300 = 2.5.

So, the average translational energy at 750 K will be:

6 x 10^-20 J x 2.5 = 1.5 x 10^-19 J