Calculate the ratio of the radius of the $2^{nd}$ and $3^{rd}$ orbit of a hydrogen atom. (Note: $r_n \propto n^2$)

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

What are the frequency and wavelength of a photon emitted during a transition from $n=5$ state to the $n=2$ state in the hydrogen atom?

The hydrogen spectrum consists of several spectral lines in the Lyman series ($L_1, L_2, L_3 \ldots$; $L_1$ has the lowest energy among the Lyman series). Similarly, it consists of several spectral lines in the Balmer series ($B_1, B_2, B_3 \ldots$; $B_1$ has the lowest energy among the Balmer lines). The energy of $L_1$ is $x$ times the energy of $B_1$. The value of $x$ is . . . . . . $\times 10^{-1}$ (Nearest integer).

The graph that depicts Einstein's photoelectric effect for a monochromatic source of frequency above the threshold frequency is

When $Z$ is doubled in an atom,which of the following statements are consistent with Bohr's theory?