Quantum theory was postulated by :

The wavelength of the second line of the Balmer series of a hydrogen atom is $\lambda \ nm$. What is the wavelength of the first line of the Lyman series of the $He^{+}$ ion (in $nm$)?

The energy of the second Bohr orbit of the hydrogen atom is $-3.4 \ eV$. The energy of the fourth Bohr orbit of the $He^{+}$ ion will be: (in $eV$)

For ionising an excited hydrogen atom,the required energy in $eV$ will be -

The ionization energy of a hydrogen atom is $13.6 \ eV$. The energy required to excite the electron in a hydrogen atom from the ground state $(n=1)$ to the first excited state $(n=2)$ is (Note: The question asks for energy per atom in Joules. Given $1 \ eV = 1.602 \times 10^{-19} \ J$)

Wave number of a spectral line for a given transition is $y \ cm^{-1}$ for $He^{+}$,then its value for $Li^{2+}$ for the same transition is