1. Element A has two isotopes. The first isotope is present 6.95% of the time and has a mass of 259.87. The second isotope has a mass of 200.17. Calculate the atomic mass of element A. (To two decimals places)

2. Element R has three isotopes. The isotopes are present in 0.0398, 0.1614, and 0.7988 relative abundance. If their masses are 198, 176, and 145 respectively, calculate the atomic mass of element R. (No decimals)

3. Element R has three isotopes. The isotopes are present in 0.0825, 0.2671, and 0.6504 relative abundance. If their masses are 89, 113, and 131 respectively, calculate the atomic mass of element R. (No decimals).

4. How many mol of C₉H₂₀ would you have if you have 53.61 grams?

5. Consider a 7.32 mol sample of C₇H₁₄. How many atoms of H would be in this sample?