Answer is: molarity of the solution is 3.902 M.
m(H₂) = 0.94 g; mass of hydrogen.
n(H₂) = m(H₂) ÷ M(H₂).
n(H₂) = 0.94 g ÷ 2.016 g/mol.
n(H₂) = 0.466 mol; amount of substance.
d(Pd) = 1.8 g/cm³; density of palladium.
V(Pd) = m(Pd) ÷ d(Pd).
V(Pd) = 215 g ÷ 1.8 g/cm³.
V(Pd) = 119.44 cm³ ÷ 1000 cm³/L = 0.11944; volume of palladium.
c = n(H₂) ÷ V(Pd).
c = 0.466 mol ÷ 0.11944 L.
c = 3.902 mol/L.