A11.0-m by 6.0-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 of22rn was 1.3 x 10-6 mmhg. calculate the number of112rn isotopes (12-3.8 days) at the beginning and end of 28 days. assume stp conditions. t-0 days: x 10rn atoms 1-28 days: x 10rn atoms