Question

how many liters of gaseous hydrogen bromide at 97 degrees c and 0.953 atm will a chemist need if she wishes to prepare 3.50 L of 1.20 M hydrobromic acid?

Answer 1

How many mols does she need? That's M x L = ?
Plug that mols (n) into PV = nRT at the conditions listed and solve for V in L.