Are my answers right? 31: What does the term half life mean?

A: The time required for half of something to undergo a process.

32: The half-life of plutonium-239 is 24,300 years. If a nuclear bomb
released 8 kg of this isotope, how many years would pass before the
amount is reduced to 1 kg?

A: It would be 72,900 years.

33: The half-life of radon-222 is 3.8 days. How much of a 100 gram
sample is left after 15.2 days?

A: It would be 6.5 g of radon-222 is left over after 15.2 days.

34: Carbon-14 has a half-life of 5,730 years. If a sample contained 70 mg originally, how much is left after 17,190 years?

A: It would be 8.75 g of C-14 will be left.

35: The half-life of cobalt-60 is 5.26 years. If 50 grams are left after 15.78 years, how many grams were in the original sample?

A: The original sample will contain 400 gms of sample.