A 14-m by 10-m by 3.0-m basement had a high radon content. On the day the basement

Question:

A 14-m by 10-m by 3.0-m basement had a high radon content. On the day the basement was sealed off from its surroundings so that no exchange of air could take place, the partial pressure of 222Rn was 1.2 × 10-6 mmHg. Calculate the number of 222Rn isotopes (t1/2 = 3.8 d) at the beginning and end of 31 days. Assume STP conditions.