The ratio of de-Brogiie wavelengths of molecules of hydrogen and helium which are at temperature 27°C and 127°C respectivell is

de-Broglie wavelength λ=hmvrms, rms velocity  of  a  gas  particle  at  the  given  temperature  (T)is  given  as12mvrms2=32KT⇒vrms=3KTm⇒mvrms=3mKT∴λ=hmvrms=h3mKT⇒λHλHe=mHeTHemHTH=4273+1272273+27=83