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 .......

The emission spectrum of hydrogen is found to satisfy the expression for the energy change $\Delta E$ (in joules) such that $\Delta E = 2.18 \times 10^{-18} \left( \frac{1}{n_1^2} - \frac{1}{n_2^2} \right) \, J$ where $n_1 = 1, 2, 3 \dots$ and $n_2 = 2, 3, 4 \dots$. The spectral lines correspond to the Paschen series when:

Calculate the radius of the third orbit of $He^{+}$. (in $pm$)

The ratio of the lowest energy in terms of wave numbers of the Balmer and Lyman series of lines of the atomic spectrum of hydrogen is

If the radius of the first orbit of a hydrogen-like ion is $1.763 \times 10^{-2} \ nm$,the energy associated with that orbit (in $J$) is

Alpha-particles that come closer to the nucleus: