The relation between the stopping potential $(V_0)$ and frequency $(v)$ is correctly represented in $[\phi = \text{Work function}]$

According to the Bohr model for the hydrogen atom,the radius of stationary orbits is proportional to which of the following?

The ratio of the radii of the $3^{rd}$ and $5^{th}$ orbits of $He^+$ is ..... . (Atomic number of $He = 2$,$r = 0.529 \times \frac{n^2}{Z} \ \mathring{A}$)

The ground state energy of a $H$ atom is given as $-13.6 \, eV$. The energy of the second excited state will be .......... $eV$.

State whether the following statements are true or false:
$(i)$ The $Bohr$ model cannot explain how atoms form molecules.
$(ii)$ The $Bohr$ model is accepted as the planetary model.
$(iii)$ Electrons in an atom do not absorb or emit energy while moving in a stationary orbit.
$(iv)$ The spectral lines of the $Brackett$ series are found in the ultraviolet region.

The energy of an electron in the first orbit of $He^+$ is $-871.6 \times 10^{-20} \ J$. The energy of an electron in the first orbit of hydrogen is ...... .