Magnesium has three known isotopes, including Mg-24, with a percent abundance of 79.0% mg-25 with a percent abundance of 11.0% and mg26 with a percent abundance of 11.0% what is the average mass ?
1) Mg-25 and Mg-26
2) Mg-23 and Mg-25
3) Mg-24 and Mg-26
4) Mg-23 and Mg-26
