How many moles of Al are there in 20g of Al2(C2O4)3?

Which statement can best be concluded from the ideal gas law?

When a chemist collects hydrogen gas over water, she ends up with a mixture of hydrogen and water vapor in her collecting bottle. if the pressure in the collecting bottle is 97.1 kilopascals and the vapor pressure of the water is 3.2 kilopascals, what is the partial pressure of the hydrogen?

You have 125 g of a certain seasoning and are told that it contains 70.0 g of salt. what is the peroentage of salt by mass in this seasoning?