Calculate the number of moles of nitrogen gas contained in a 4.5 L vessel at 275 K with a pressure of 3.25 atm? Help I don't know how t solve this

No copying 15 pts how does a free-body diagram tell you about the net force on an object?

What happens in the particles of a gas when the gas is compressed

Awhite powder is added to a solution. the images show observations made before the powder is added, just after the powder has been added, and a little while later. (the liquid in the small beaker is phenol red solution.) what evidence shows that a chemical change has taken place?