The half-life, t 1/2, of 222Ra is 4.0 days and 1.0g of this isotope is present. How much 222Ra could we expect

Question

The half-life, t 1/2, of 222Ra is 4.0 days and 1.0g of this isotope is present. How much 222Ra could we expect to be present after 4.0 weeks? can you please write down how you got the answer, so i can understnad how to do it!! thanks a million!

Answer 1

Every 4 days half of what's left will disappear.

4 weeks = 28 days. So the amount will be cut in half 7 times.

Calulate 1/2 E 7 (1/2 x 1/2 ...)and you will have the fraction remaining of the original 1.0 grams