1. if you have a 1-g sample of po-218, how many grams would you
have after 6 minutes? after 18 minutes?

a) 0.25 g b) 0.01542 g

Explanation:

Half life of Po-218 = 3.04 minutes

initial mass = 1 g

after 3.04 minutes it will remain 0.5 g

after another 3.04 minutes it will remain 0.25 g

After 6 minutes it will remain approx 0.25 g

B) after another 3.04 minutes it will remain 0.125 g

after another 3.04 minutes it will remain 0.0625 g

after another 3.04 minutes it will remain 0.03125 g

after another 3.04 minutes it will remain 0.015625 g

After 18 minutes it will remain approx 0.01542 g

a 20-cm-long, cylindrical graphite (pure carbon) rod is inserted into an oxidizing atmosphere at 1145 k and 1.013 x 105 pa pressure. the oxidizing process is limited by the diffu- sion of oxygen counterflow to the carbon monoxide that is formed on the cylindrical surface.