Answer: radon (atomic mass 222 amu
Explanation:
To calculate the rate of diffusion of gas, we use Graham's Law.
This law states that the rate of effusion or diffusion of gas is inversely proportional to the square root of the molar mass of the gas. The equation given by this law follows:
atomic mass of krypton= 83.8 amu
atomic mass of argon= 39.95 amu
atomic mass of xenon = 131.3 amu
atomic mass of radon= 222 amu
Thus as atomic mass of radon is highest, its rate of diffusion is slowest.