Co-60 has a half life of 10.48 minutes. how long will it take for the isotope to decay to 1/64th of its original quantity?

The answer to your question is: 62.88 min

Explanation:

Data

Co - 60

half-life = 10.48 min

decay = 1/64 th

Process

1      

2     1 half life              1/2                         10.48

3     2 half life             1/4                         20.96

4     3 half life             1/8                         31.44

5     4 half life             1/16                        41.92

6     5 half life             1/32                       52.4

7      6 half life            1/64                        62.88

uranium-238 i believe is your answer

c is the answer because when something is left after something evaporates that shows the chemical change.