1. The formula of the ionic compound that forms from two ions, A2+ and R9-, can be written as AxRy. What is the value of x?

Only enter the numerical answer for x. Answer must be a whole number

2. A specific radioactive isotope has a half-life of 15.2 minutes. How long will it take this isotope to decay to 1/8 of its original amount?

Do not include units. 2 decimal places.

3. Two short-lived isotopes of an element are produced in a nuclear reaction. One of the isotopes has a mass of 5.3731 amu and accounts of 77.5% of the production. The remaining other isotope has a mass of 7.3904 amu. Use this information to calculate the atomic mass of this element.