Question

Americium-241 is a radioactive substance used in smoke detectors. The half life of americium is 432 years. If a smoke detector initially contains 1 gram of Americium 241, how much will remain in 432 years? A) 0.5g B) 1.0g C) 1.5g D) 2.0g

Answer 1

The half life of americium is 432 years. That means that after 432 years only half(1/2) of initial amount will be left.
If we had 1 g, then after 432 years we will have only half of it.
1g*1/2=1/2 g=0.5 g
Answer is A) 0.5g