Answer :

SoapyMcTavish
In a standard temperature and pressure, 1 mole of Gas takes a bout 22.4 liters.
So we get: 
1 mole = 22.4 liters
4.5 moles = x liters. 
x = 100.8 (With the Volume of 4.5 moles)
So, 4.5 moles of H2 have a volume of 100.8 liters.
Hope this Helps :)