The energy of an electron in the first orbit of a hydrogen atom is $-13.6 \ eV$. The possible energy value for an electron in the excited state is ............ $eV$.

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

Calculate the radius of the first orbit of $Be^{3+}$. (in $pm$)

In the transition of an electron in an atom,its kinetic energy changes from $y$ to $y/4$. The change in potential energy $(P.E.)$ will be:

An electron in an atom jumps in such a way that its kinetic energy changes from $x$ to $\frac{x}{4}$. The change in potential energy will be

The minimum energy that must be possessed by photons in order to produce the photoelectric effect with platinum metal is $.... \times 10^{-19} \, J$
[Given: The threshold frequency of platinum is $1.3 \times 10^{15} \, s^{-1}$ and $h = 6.6 \times 10^{-34} \, J \, s$.]