According to Bohr's theory,the electron in orbits has definite energy values. Then,according to the uncertainty principle,the lifetime of an excited state will be:

In the Davisson-Germer experiment,an electron beam of energy $75 \ eV$ falls normally on the surface of a crystal. If the maximum intensity is obtained at an angle of $45^o$ to the direction of the incident beam,then the inter-atomic distance in the lattice plane of the crystal will be .............. $\mathring{A}$

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:

Consider two separate ideal gases of electrons and protons having the same number of particles. The temperature of both gases is the same. The ratio of the uncertainty in determining the position of an electron to that of a proton is proportional to :-

In the Davisson-Germer experiment,the nickel crystal acts as a .........

In the Davisson-Germer experiment,the deflection of the galvanometer is proportional to which quantity?