CBSE Class 12-science Answered

(c) (3/8)

de Broglie wavelength, λ = h/(2πmkT)

where h - Planck's constant, m - mass of atom, k - Boltzmann constant, T - temperature in K.

Hydrogen molecules, H₂, will have 2 protons,

Helium molecules will have 2 protons and 2 neutrons. Masses of protons and neutrons are approximately same. Hence Helium gas molecule will be TWICE massive than hydrogen molecule.

λHydrogen/λHelium = [(mT)_Hydrogen/(mT)_Helium] = (300/(2x400)) = (3/8)

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