In the Davisson-Germer experiment,an electron beam with a wavelength of $1.5 \ \mathring{A}$ is incident normally on a crystal with an atomic spacing of $3 \ \mathring{A}$. At what angle (in degrees) will the first maximum be formed?

$A$ sodium atom is in one of the states labeled 'Lowest excited levels'. It remains in that state for an average time of $10^{-8} \, s$,before it makes a transition back to a ground state. What is the uncertainty in energy of that excited state?

In the Davisson-Germer experiment,when electrons strike a $Ni$ crystal,which of the following waves are diffracted?

The wave property of electrons implies that they will show diffraction effects. Davisson and Germer demonstrated this by diffracting electrons from crystals. The law governing the diffraction from a crystal is obtained by requiring that electron waves reflected from the planes of atoms in a crystal interfere constructively (see figure).

The Davisson-Germer experiment is the direct evidence of

Given below are two statements :-
Statement $I$ : Davisson-Germer experiment establishes the wave nature of electrons.
Statement $II$ : If electrons have wave nature,they can interfere and show diffraction.
In the light of the above statements,choose the correct answer from the options given below: