7. A specific radioactive isotope has a half-time of 30.2 minutes. How long will it take this isotope to decay to 1/8 of its original amount?

7.

A specific radioactive isotope has a half-time of 30.2 minutes. How long will it take this isotope to decay to 1/8 of its original amount?

9. The formula of the ionic compound that forms from two ions , 

A 2+ and R 7-, can be written as AxRy.

What is the value for the x?