Thomson's atomic model is also known as .....

Which of the following corresponds to the energy of a possible excited state of hydrogen (in $eV$)?

Which of the graphs shown below does not represent the relationship between incident light and the electron ejected from a metal surface?

The ratio between the radii of $He^{+}$ ion and $H$ atom is:

The wavelength of the first line of the Lyman series for hydrogen is $1216 \ \mathring{A}$. The wavelength of the first line of the same series for a $10$ times ionized sodium atom $(Z = 11)$ will be ......... $\mathring{A}$.

Four lowest energy levels of $H$-atom are shown in the figure. The number of emission lines could be obtained by transitions from these levels. The total number of possible emission lines is: