Question

The following isotopes (listed with their half-lives) have been used in the medical and biological sciences. Arrange these isotopes greatest to least decay activity. (Use the appropriate <, =, or > symbol to separate substances in the list.)

^3H (12.2 years)
^24Na (15 years)
^131I (8 days)
^60Co (5.3 years)
^14C (5730 years)

Answer 1

This looks easy enough. Wouldn't you think the one with the greatest decay rate (8 days) would be first and the one with the longest decay rate (5,730 years) would be last?

Answer 2

^60Co < ^131I < ^3H < ^24Na < ^14C

Answer 3

3H>24Na>131I>60Co>14C