The kinetic energy of an electron in the ground state of a $Be^{3+}$ ion is given by:

Newtonian mechanics is applicable to which objects and not applicable to which objects?

When a hydrogen atom in an excited state undergoes electronic transitions to the ground state,$5$ spectral lines are observed in the ultraviolet region. How many spectral lines will be observed in the infrared region due to transitions from the same excited state?

For a hydrogen atom,the energy of an electron in the first excited state is $-3.4 \ eV$. The kinetic energy $(KE)$ of the same electron in the hydrogen atom is $x \ eV$. The value of $x$ is . . . . . . $\times 10^{-1} \ eV$. (Nearest integer)

If $\lambda_0$ and $\lambda$ are the threshold wavelength and the wavelength of incident light,respectively,the velocity of the photoelectron ejected from the metal surface is:

If the shortest wavelength in the Lyman series of a hydrogen atom is $A$,then the longest wavelength in the Paschen series of $He^{+}$ is: