Matter Waves: a Gas of Helium Atoms (Each of Mass

Multiple Choice

Matter waves: A gas of helium atoms (each of mass 6.65 × 10^-27 kg) are at room temperature of 20.0°C. What is the de Broglie wavelength of the helium atoms that are moving at the root-mean-square speed? (h = 6.626 × 10^-34 J ∙ s, the Boltzmann constant is 1.38 × 10^-23 J/K)

A) 5.22 × 10^-11 m
B) 7.38 × 10^-11 m
C) 1.04 × 10^-10 m
D) 2.82 × 10^-10 m
E) 3.99 × 10^-10 m