Question

The table below compares the radioactive decay rates of two materials.

Material Original mass of material (in grams) Mass of material after 60 hours (in grams)
1 208 13
2 200 50
Based on the table, which of these conclusions is most likely correct?

The half-life of Material 1 and Material 2 are equal.
The half-life of Material 2 is double the half-life of Material 1.
The half-life of Material 2 is 30 hours more than the half-life of Material 1.
The half-life of Material 1 is 30 hours more than the half-life of Material 2.

Answer 1

In 60 hours, sample 1 went through 4 half lives (13/208 = 1/16 = 1/2 * 1/2 * 1/2* 1/2)
In 60 horus, sample 2 went through 2 half lives (50/200=1/4 = 1/2 * 1/2)

Thus, sample 1 has a half life of 60/4 = 15h
and sample 2 has a half life of 60/2 = 30h

so answer is: The half-life of Material 2 is double the half-life of Material 1.

Answer 2

Thank you so very much! :P