Question

If there are 50 grams of U-238 on day zero of radioactive decay, how much will there be after 4.5 billion years? A) 0.0 grams B) 10 grams C) 25 grams D) 50 grams

Answer 1

C) 25 grams

Step-by-step explanation:

25 grams would remain after one half-life (4.5 billion years). Find the point where percent remaining is 50% and that will tell you it is one half-life.

Answer 2

= 25 g

Step-by-step explanation:

Using the formula;

A = A₀ (1/2)^(t/h)

where A is the final amount,

A₀ is the initial amount of the substance,

t is the time and

h is the half-life of the substance,

In this case; the half life of U-238 h is equal to 4.47 billion years.

A = A₀ (1/2)^(t/h)

A = 50 (1/2)^(4.5 / 4.47)

= 24.88

= 25 g