A container of fixed volume has mixture of one mole of hydrogen and one mole of helium in equilibrium at temperature T. Assuming the gases are ideal, the correct statement(s) is (are)

(A) Total internal energy  U=f12nRT+f22nRT Uaveper mole=U2n=145RT+3RT=2RT(B)  γmix=n1CP1+n2CP2n2CV1+n2CV2=17R2+15R215R2+13R2=32Mmix=n1M1+n2M2n1+n2=M1+M22=2+42=3Speed of sound  V=γRTM⇒V∝γMVmixVHe=γmixγHe×MHeMMix=3/25/3×43=65 (D)  Vrms=3RTM⇒Vrms∝1M,  VHeVH=MHMHe=24=12