If a sample is thought to be several million years old, which method would best to determine its absolute age? a. c-14/c-12 b. ar-40/k-40 c. pb-206/u-238

Compare and contrast physical changes with chemical changes.

12. calculate the hydroxide ion concentration of a solution with ph = 3.25. show all calculations leading to an answer

Butane gas reacts with oxygen gas to give carbon dioxide gas and water vapor (gas). if you mix butane and oxygen in the correct stoichiometric ratio, and if the total pressure of the mixture is 390 mmhg, what is the pressure (in mmhg) of water vapor after the reaction is completed (temperature and volume do not change).