One way of separating oxygen isotopes is by gaseous diffusion of carbon monoxide. the gaseous diffusion process behaves like an effusion process. calculate the relative rates of effusion of 12c16o, 12c17o, and 12c18o. list

Rates of effusion of gases is governed by the Graham's Law. This law relates the ratio of the rates of effusion to the ratio of the molar masses of the gases involved. With the assumption that pressure and temperature are similar for both gases, the Graham's law states that,
     (rate of Gas A)/(rate of Gas B) = (molar mass of Gas B)^1/2 / (molar mass of Gas A)^1/2

Substituting the known values to the equation.

Part A:
   rate of C12/ rate of O16 = sqrt (16/12) = 1.1543

The rate of C12 is 1.15 faster than O16.

Part B:
   rate of C12/ rate of O17 = sqrt (17/12) = 1.19

The rate of C12 is 1.19 faster than O17.

Part C:
   rate of C12/rate of O18 = sqrt (18/12) = 1.22
The rate of C12 is 1.22 faster than O18. 

29.1-12=17.1the answer is this one