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?
question 4 options:
0.5 grams
1.0 grams
1.5 grams
2.0 grams

Answer : The correct option is, (2) 0.5 grams

Solution : Given,

As we know that the radioactive decays follow first order kinetics.

First we have to calculate the half life of Americium-241.

Formula used :

Putting value of half-life in this formula, we get the rate constant.

The expression for rate law for first order kinetics is given by :

where,

k = rate constant  =

t = time taken for decay process  = 432 years

a = initial amount of the Americium-241 = 1 g

a - x = amount left after decay process  = ?

Putting values in above equation, we get

Therefore, the amount remain in 432 years will be, 0.5 grams

- both b and d.

-since b and d are the closest coastlines then that makes it the most affected.

< 3

the answer would be b i believe