The energy required for the ionisation of a hydrogen atom is $13.6 \ eV$. What is the energy required for the ionisation of $He^+$ ion (in $eV$)?

Assertion : For Balmer series of hydrogen spectrum,the value $n_1 = 2$ and $n_2 = 3, 4, 5...$
Reason : The value of $n$ for a line in Balmer series of hydrogen spectrum having the highest wavelength is $4$ and $6$.

Write down the postulates of Bohr's model for the hydrogen atom.

The ratio of the maximum wavelengths of the Lyman and Balmer series is ....

What is the energy (in $J$ atom$^{-1}$) required for the following process?
$Li^{2+}(g) \to Li^{3+}(g) + e^-$
(Take the ionization energy for the $H$ atom in the ground state as $2.18 \times 10^{-18}$ $J$ atom$^{-1}$)

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