According to the Rutherford’s atomic model, the electrons inside the atom are

In a Geiger-Marsden experiment, what is the distance of closest approach to the nucleus of a $7.7 \;MeV$ $\alpha -$particle before it comes momentarily to rest and reverses its direction?

Ratio of longest wavelengths corresponding to Lyman and Balmer series in hydrogen spectrum is

Ionization potential of hydrogen atom is $13.6 V$. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy $12.1 eV.$ The spectral lines emitted by hydrogen atoms according to Bohr's theory will be

According to the classical electromagnetic theory, calculate the initial frequency of the light emitted by the electron revolving around a proton in hydrogen atom.

The number of completely filled shells for the element ${ }_{16} S ^{32}$ is