If 12.0g of molecular oxygen, O2, is required to inflate a balloon to a certain size at 27 degree celcius, what mass of molecular oxygen required to inflate it to the same size and pressure at 81 degree celcius?

Answer 1

Convert 12.0 g oxygen to moles and use PV=nRT to solve for n.
Then use PV-nRT a second time but substitute the nhew temperature. You can make up values for P and V (I would use 1 and 1) and use the same numbers for both sets of values since the P and V don't change.