For the hydrogen atom, the transition from \(n = 1\) to \(n = 3\) gives the radiation in the Balmer series:
\[ \Delta E = 12.1 \, \text{eV} \]
Thus, the correct answer is Option (4).
A hydrogen atom in the ground state (n=1) must first absorb energy to reach an excited state from which a transition to n=2 (first excited state) results in the emission of a Balmer series spectral line. We need to find the minimum energy required for this process.
The energy of an electron in the nth orbit of a hydrogen atom is given by the Bohr model formula:
\[ E_n = -\frac{13.6}{n^2} \ \text{eV} \]
Step 1: Write the energies of the relevant levels.
\[ E_1 = -\frac{13.6}{1^2} = -13.6 \ \text{eV} \] \[ E_3 = -\frac{13.6}{3^2} = -\frac{13.6}{9} \ \text{eV} \]
Step 2: Calculate the energy difference for the transition from n=1 to n=3.
\[ \Delta E = E_3 - E_1 = \left(-\frac{13.6}{9}\right) - (-13.6) = 13.6 - \frac{13.6}{9} \] \[ \Delta E = 13.6 \left(1 - \frac{1}{9}\right) = 13.6 \times \frac{8}{9} \]
Step 3: Compute the numerical value.
\[ \Delta E = \frac{108.8}{9} \approx 12.0889 \ \text{eV} \]
This value is approximately 12.1 eV.
Thus, the minimum energy required by a hydrogen atom in the ground state to emit radiation in the Balmer series is nearly 12.1 eV.
A black body is at a temperature of 2880 K. The energy of radiation emitted by this body with wavelength between 499 nm and 500 nm is U1, between 999 nm and 1000 nm is U2 and between 1499 nm and 1500 nm is U3. The Wien's constant, b = 2.88×106 nm-K. Then,

What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)