Theoretical element “A” has four isotopes. Use the data in the table to calculate the average atomic mass of the unknown element A. All steps of the calculations must be shown for credit.

1. and 2. question: in which equation? or i don't understand you, 3. a), 4. c), 5. c), 6. b), 7. d), 8. d) if small number is underlined(behind symbol) , b) if big number is underlined(in front of symbol)9. what is underlined there? 10. c)

The answer is d- principle of faunal succession.

Hi + naoh -> h2o + nal