Which of the following formula(s) best represent(s) Graham's law?

I.
II.
III.
IV.

a. 1 c. 2 and 4
b. 3 d. 3 and 4

ANS: C
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. If the mass of a gas is considered directly proportional to its density at a constant temperature and pressure, then 2, where d1 and d2 are the densities of the gases in ques-tion.