How do you count atoms when there's leading coefficient?

4moles of nitrogen gas are confined to a 6.0 l vessel at 177 °c and 12.0 atm. if the vessel is allowed to expand isothermally to 36.0 l, what would be the final pressure?

What is the energy in joules of a mole of photons associated with visible light of wavelength 486 nm?

What kind of intermolecular forces act between a hydrogen fluoride molecule and a hydrogen peroxide molecule? note: if there is more than one type of intermolecular force that acts, be sure to list them all, with a comma between the name of each force.