How much cesium (half-life = 2 years) would remain from a 10 g sample after 6 years?
O A. 59
O B. 119
O c. 2 1 2
O D.09

The correct answer is A. 59.

Explanation:

The formula for finding the amount of radio active substance that remains after decomposition is A = N(1/2) ^y, where A is the mass remaining, N is the original mass of a radioactive sample and y is the number of half life. In this case, N = 10 g and y = 6/2 = 3. So A is given by 10 x (1/2)^3, which is 10 x 1/2 x1/2 x 1/2 = 1.25 grams.