A container holds a pure sample of a radioactive substance with a half-life of 2 hours.
Part A
Which of the following statements are true?
a) After 1 hour, less than 50% of the original atoms in the container will have decayed.
b) After 1 hour, more than 50% of the original atoms in the container will have decayed.
c) After 2 hours, 50% of the original atoms in the container will have decayed.
d) After 4 hours, 25% of the original atoms will have decayed.
e) After 4 hours, the total number of atoms in the container will be reduced by 75%.
Answer: A and C

In addition to the sample mentioned in Part A, consider a pure sample of a different radioactive substance that has a half-life of 1 hour. Assume that you initially have twice as many atoms of this new sample as you have of the previous sample. The table below summarizes this information:

Sample Half-life (hours) Original number of atoms
A 2 N_0
B 1 2N_0

Part B
Which of the following statements about samples A and B are true?

a) After 1 hour, a larger percentage of undecayed atoms will be left in sample A than in sample B.
b) After 1 hour, a larger number of atoms will have decayed in sample B than in sample A.
c) After 2 hours, the same number of atoms will have decayed in both samples.
d) After 2 hours, both samples will have the same number of undecayed atoms.

Answer rating: 100% (QA)

The detailed answer for the above question is provided below Answer b Afte... View the full answer