The relation between the stopping potential $(V_0)$ and frequency $(v)$ is correctly represented in $[\phi = \text{Work function}]$

Heat treatment of muscular pain involves radiation of wavelength of about $900 \ nm$. Which spectral line of $H$ atom is suitable for this? Given: Rydberg constant $R_{H}=10^5 \ cm^{-1}, h=6.6 \times 10^{-34} \ J \ s, c=3 \times 10^8 \ m / s$.

The radius of the second Bohr orbit for hydrogen atom is .......... $\mathring{A}$.
(Planck's constant $h = 6.626 \times 10^{-34} \, Js$; mass of electron $= 9.1091 \times 10^{-31} \, kg$; charge of electron $e = 1.60210 \times 10^{-19} \, C$; permittivity of vacuum $\epsilon_0 = 8.854185 \times 10^{-12} \, C^2 N^{-1} m^{-2}$)

The ionization enthalpy of a hydrogen atom is $1.312 \times 10^6 \ J \ mol^{-1}$. The energy required to excite the electron in the atom from $n= 1$ to $n= 2$ is

What is the experimental evidence in support of the idea that electronic energies in an atom are quantized?

The ratio of ground state energy of $Li^{2+}$,$He^{+}$,and $H$ is: