Question

Suppose a laboratory has a 26 g sample of polonium-210. The half-life of polonium-210 is about 138 days. How many half-lives of polonium-210 occur in 276 days? How much polonium is in the sample 276 days later?

2; 6.5 g

3; 3.25 g

2; 1,794 g

2; 13 g

Answer 1

276/138=2 halflives

after 1st halflife , 26/2=13 g is left
after 2nd half life, 13/2 = 6.5 g is left