Average Atomic Mass Calculations

Find the average atomic mass for Mg if 78.99% of Mg atoms are ²⁴Mg with a mass of 23.9850419 amu, 10.00% are ²⁵Mg with a mass of

24.9858370 amu, and 11.01% are ²⁶Mg with a mass of 25.9825930 amu. (Round to three decimal places)

Find the average atomic mass for Cl if 75.78% of Cl atoms are ³⁵Cl with a mass of 34.96885271 amu and 24.22% are ³⁷Cl with a mass of 36.96590260 amu. (Round your answer to three decimal places.)

There are 2 isotopes of copper that occur naturally; ⁶³Cu and ⁶⁵Cu. The

⁶³Cu atoms have a mass of 62.929601 amu and the ⁶⁵Cu atoms have a mass of 64.927794 amu. What is the percent natural abundance for the ⁶⁵Cu isotope? (Round your percentage to two decimal places and include the % symbol in your answer.)