Question

Two 1 liter flasks contain hydrogen and oxygen, respectively, at the same temperature and pressure. It is true that the hydrogen and oxygen molecules have the same average
(1) kinetic energy
(2) mass
(3) speed

• A. If 1, 2 and 3 are correct
• B. If only 1 and 2 are correct
• C. If only 2 and 3 are correct
• D. If only 1 is correct
• E. If only 3 is correct

Answer 1

The correct option is D If only 1 is correct

Under the same condition of temperature, all gases will have the same average kinetic energy. It is given by the formula

$\frac{3}{2}$$kT$

Although, both the gases are at the same condition of temperature and pressure, and they occupy the same volume, the number of moles will be the same in both the cases. But their mass will not be the same.

And, hydrogen and oxygen will have different speed too.

Thus, only their average kinetic energy is the same.

Hence, option D is the correct answer.