There is more than one isotope of natural uranium. If a researcher isolates 1.00 mg of the relatively scarce U and finds this mass to have an activity of 80.0 Bq, what is its half-life in years? (answer in ×10 y)

A piece of charcoal used for cooking is found at the remains of an ancient campsite. A 1.19 kg sample of carbon from the wood has an activity of 2340 decays per minute. Find the age of the charcoal. Living mate- rial has an activity of 15 decays/minute per gram of carbon present and the half-life of 14C is 5730 y. Answer in units of y.

There is more than one isotope of natural uranium. If a researcher isolates 0.7 mg of the relatively scarce 235U and finds this mass to have an activity of 78.0 Bq, what is its half-life in years? =___years

(a) At an initial time, a radioactive sample has an activity of 8.52x104 Bq. After 3.85 hours the activity is 5.42×104 Bq. (A) What is the half-life of the isotope? (B) What is the activity after an additional 3.85 hours? (A) (in s) OA: 2.285x103 (B) (in Bq) OA: 1.149x104 OB: 3.314x103 OB: 1.344x104 OC: 4.805x103 OC: 1.573x104 OD: 6.967x103 OD: 1.840x104 OE: 1.010x104 OE: 2.153x104 OF: 1.465x104 OG: 2.124x104 OF: OG: 2.519x104 2.947x104 OH: 3.080x104 OH: 3.448x104