The half-life of strontium-91, 9138Sr, is 9.70 h. (a) Find its decay constant (in s−1). (b) For an initial 1.18 g sample, find the activity (in decays/s) after 19 hours.

A sample of radioactive isotope is found to have an activity of 110 Bq imediately after it is pulled from the reactor that formed the isotope. Its activity 1 h, 20 min later is measured to be 89 Bq. Find the decay constant of the sample. Answer in units of h-. Find the half-life of the sample. Answer in units of h. How many radioactive nuclei were there in the sample initially?

Question 2. A piece of charcoal used for cooking is found at the remains of an ancient campsite. A 1.00 kg sample of carbon from the wood has an activity equal to 5.00 x 10* decays per minute. Find the age of the charcoal. Hint: Living material has an activity equal to 15.0 decays/min per gram of carbon present.

The half-life of Ra-226 is 1.60 x 10^3 years = 5.05 x 10^10 s Find k What is the activity in curies of a 1.00 g sample? What is the mass in grams of a Ra-226 sample that has an activity of 1.00 x 10^9 atoms/min?