The energy of an electron in the first Bohr orbit of the $H$ atom is $-13.6 \ eV$. The magnitude of the energy value of an electron in the first excited state of $Be^{3+}$ is $.......... \ eV$ $(nearest \ integer \ value)$.

The maximum wavelength of radiation that can ionise a sodium atom is $2414 \ \mathring{A}$. The ionisation energy of sodium per mole shall be

If the energy of a photon is $14 \, eV$ and it interacts with a hydrogen atom,which of the following is correct?

Choose the correct option regarding: Assertion: Energy of the orbital decreases with increase of $n$.
Reason: Energy is required in shifting away the negatively charged electron from the positively charged nucleus.

Evaluate the following ratios for the energy of the electron in a particular orbit:
[Kinetic $:$ Potential] and [Total $:$ Kinetic]

In Rutherford's experiment,generally the thin foil of heavy atoms,like gold,platinum etc. have been used to be bombarded by the $\alpha$-particles. If the thin foil of light atoms like aluminium etc. is used,what difference would be observed from the above results?