If the wavelength of the first line of the Balmer series of hydrogen is $6561 \stackrel{\circ }{\mathrm{A}}$, the wavelength of the second line of the series should be?

The energy level diagram for a hydrogen-like atom is shown in the figure. The radius of its first Bohr orbit is

The following diagram indicates the energy levels of a certain atom when the system moves from $4E$ level to $E$. A photon of wavelength ${\lambda }_1$ is emitted. The wavelength of photon produced during its transition from $\frac{7}{3}E$ level to $E$ is ${\lambda }_2$. The ratio $\frac{{\lambda }_1}{{\lambda }_2}$ will be

Energy levels $A$, $B$, $C$  of a certain atom corresponding to increasing values of energy, i.e., $E_A<E_B<E_C$. If ${\lambda }_1$, ${\lambda }_2$ and ${\lambda }_3$ are the wavelengths of radiations corresponding to the transitions $C$ to $B$, $B$ to $A$ and $C$ to $A$ respectively, which of the following statements is correct

Figure shows the energy levels $P$, $Q$, $R$, $S$ and $G$ of an atom, where $G$ is the ground state. A red line in the emission spectrum of the atom can be obtained by an energy level change from $Q$ to $S$. A blue line can be obtained by the following energy level change

The figure indicates the energy level diagram of an atom and the origin of six spectral lines in emission (e.g. line no. $5$ arises from the transition from level $B$ to $A$). The following spectral lines will also occur in the absorption spectrum