What is the number of moles of gas contained in a 3.0L container at 3.00x102K with a pressure of 1.5 atm?

Which buffer would be better able to hold a steady ph on the addition of strong acid, buffer 1 or buffer 2? explain. buffer 1: a solution containing 0.10 m nh4cl and 1 m nh3. buffer 2: a solution containing 1 m nh4cl and 0.10 m nh3

If anyone would be able to me out with these three questions it would be these are from the chem 2202 course.

How many moles is 14.5 cm^3 of platinum? the density of platinum is 21.45 g/cm^3.