Pls help file attached

At stp, what is the volume of 1 mole of co2?

How would the number of moles (n) of o2 change if the atmospheric pressure doubled but all other variables stayed the same

A5.000 g sample of niso4 h2o decomposed to give 2.755 g of anhydrous niso4. what is the formula of the hydrate? what is the full chemical name for the hydrate? what is the molar mass of the hydrate? niso4•_h2o what is the mass % of water in the hydrate?