The ratio of ionisation energy of Bohr's Hydrogen atom and Bohr's Hydrogen-like Lithium atom is,

Which of the following statements are true regarding Bohr's model of hydrogen atom?

$\left(\mathrm{I}\right)$ Orbiting speed of electron decreases as it shifts to discrete orbits away from the nucleus.

$\left(\mathrm{II}\right)$ Radii of allowed orbits of electron are proportional to the principal quantum number.

$\left(\mathrm{III}\right)$ Frequency with which electrons orbit around the nucleus in discrete orbits is inversely proportional to the cube of principal quantum number.

$\left(\mathrm{IV}\right)$ Binding force with which the electron is bound to the nucleus increases as it shifts to outer orbits.

Select the correct answer using the codes given below