Solve the following problem:
Problem: For this problem, you will calculate the activity of a radioactive substance at different times. The half-life of the radioactive nucleus 22688 Ra is 2 x 102 yr. If a sample initially contains 2 x 1015 such nuclei,
(a) Determine the initial activity in curies.
(b) Determine the number of radium nuclei remaining after 5 x 102 yr?
(c) Determine the activity at this later time.
Explain the each and every step in derail for help. Thanks.