Help in chemistry please

what pressure does 10.5 grams of hydrogen exert in a 750.0 ml flask at 20.0 C?

10.5 grams is 10.5g/2 g/mole = 5.25 moles

1 mole at STP occupes 22.4 L

so we have squeezed it 1atm * 5.25 * 22.4/0.75 * (273+20)/273 (this is temp correction) = 168 atm

PV = nRT

n = grams H2 / MM of H2
R= Ideal Gas Constant
P = Pressure
V = Volume in Liters