Answer:
B) 10.5
Explanation:
PV= NRT Â Â -> N=PV/RT
N= mols .   P= pressure . V= volume in Liters   T= temp in Kelvin (Celsius degree = 273.15) .  R= Gas constant (.0821 for atm)
N=(.77 x 65.5)/(.0821x235) = 2.614 mols of Helium
Mols x Molecular weight = weight in grams
2.614x4.003(Molecular weight ot He) = 10.46 round to 10.5 Â