The volume that will occupy at STP is calculated as follows by use of ideal gas equation that is PV=nRT where n is number of moles calculate number of moles
n= PV/RT p=0.75 atm V=6.0 L R = 0.0821 L.atm/k.mol T= 35 +273= 308k n=?
n= (o.75 atm x 6.0 L)/( 0.0821 L.atm/k.mol x 308 k)= 0.178 moles