Answer : The correct option is, Both gases have the same average kinetic energy.
Explanation :
As we are given that there are 8 moles of 'He' and 'Xe'.
At STP condition,
The temperature and pressure are 273 K and 1 atm respectively.
The formula of average kinetic energy is,
. From this we conclude that the average kinetic energy is depends on the temperature only. So, at same temperature the average kinetic energy will also be same for both the gases.
As we know that the molecular speed is inversely proportional to the square root of the molecular mass. That means, it depends on the molar mass of substance. So, both the gases have the different molecular speed.
As we know that the density is directly proportional to the mass of substance. That means, it depends on the mass of substance. So, both the gases have the different density.
At STP,
As, 1 mole of He gas contains 22.4 liter volume of He gas
So, 8 mole of He gas contains
liter volume of He gas
As, 1 mole of Xe gas contains 22.4 liter volume of Xe gas
So, 8 mole of Xe gas contains
liter volume of Xe gas
The mixture of has volume = 179.2 + 179.2 = 358.4 L
Hence, from the above we conclude that the correct option is, Both gases have the same average kinetic energy.