When the colors of light are mixed, they produce the color: red black white violet

Which statement describes both homogeneous mixtures and heterogeneous mixtures?

11. phosphorus-32 is radioactive and has a half life of 14 days. how much of a 124 mg sample of phosphorus-32 is present after 56 days? a) 7.75 mg b) 15.5 mg c) 31.0 mg d) 62.0 mg

What is the independent variable in this investigation? mass volume sample number substance density