Calculate the energy in calories required to produce, from neutral $\mathrm{He}$ atoms, $1$ mole of:

(a) ${\mathrm{He}}^{+}$ ions

(b) ${\mathrm{He}}^{++}$ ions

using Bohr's equations.

Write your answer in form of $1.248\times {10}^{\mathrm{x}} \mathrm{cal}/\mathrm{mol}$ value of x will be.

Calculate the energy in $\mathrm{eV}$ required to ionise $1 \mathrm{mole}$ of hydrogen.

Round off your answer to the nearest integer.

The frequency of the spectral line when an electron from the fifth orbit jumps to the second orbit in a hydrogen atom is   $6.913\times {10}^{\mathrm{n}}$ $\mathrm{Hz}$, then find the value of $\mathrm{n}$. Give an answer to nearest integer value.

${\mathrm{R}}_{\mathrm{H}} = 109737 {\mathrm{cm}}^{-1}$

Find the total mass(in mg) of neutrons in $7 \mathrm{mg}$ of ${}^{14}\mathrm{C}$. (Assume the mass of a neutron$=$mass of a hydrogen atom)

Report your answer as the nearest integer.

Calculate the frequency, energy and wavelength of the radiation corresponding to the spectral line of lowest frequency in Lyman series in the spectra of hydrogen atom. Also, calculate the energy for the corresponding line in the spectra of ${\mathrm{Li}}^{+2}$

$\left({\mathrm{R}}_{\mathrm{H}}=1·09678\times {10}^7 {\mathrm{m}}^{-1}, \mathrm{c}=3\times {10}^8 \mathrm{m}/\mathrm{s},Z=3, \mathrm{h}=6·625\times {10}^{-34}\mathrm{J}·\mathrm{s}\right)$