Question

If $H_2$ He, $O_2$ $N_2$ travel with the same velocity then the longest de-broglie wavelength should be associated with

Answer 1

As we know that de-broglie wavelength =h/momentum.

=h/mv

and all these are moving with same velocity,then deb broglie wavelength will depend on the mass.

smallest mass will have largest de-broglie wavelength.

Thus hydrogen will have largest de broglie wavelength.