Which law states that when two gases are placed under the same temperature and pressure, the rates of diffusion of both gases are inversely proportional to the square root of their densities?

a. Graham's law
b. Henry's law
c. Mole's law (also known as the ideal gas law)
d. Fick's law

ANS: A
Graham's law states that when two gases are placed under the same temperature and pressure conditions, the rates of diffusion of the two gases are inversely proportional to the square root of their masses, or = , where r1 and r2 represent the diffusion rates of the respective gases and M1 and M2 are the molar masses.