In the $n^{th}$ orbit, the energy of an electron $E_{\mathrm{n}}=-\frac{13.6}{n^2} \mathrm{eV}$ for hydrogen atom. The energy required to take the electron from the first orbit to the second orbit will be

Energy levels $A, B$ and $C$ of a certain atom corresponding to increasing values of energy, i.e., $E_{\mathrm{A}}<E_{\mathrm{B}}<E_{\mathrm{C}}$. 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 which of the following energy level change?