Question:

The energy required (in eV) to excite an electron of H-atom from the ground state to the third state is

Show Hint

For hydrogen atom, \[ E_n=\frac{-13.6}{n^2}\,\text{eV} \] Excitation energy is always calculated using \[ \Delta E=E_f-E_i \] where \(E_f\) is the final energy level and \(E_i\) is the initial energy level.
Updated On: Jun 22, 2026
  • \(+0.85\)
  • \(-3.4\)
  • \(12.1\)
  • \(-12.1\)
Show Solution
collegedunia
Verified By Collegedunia

The Correct Option is C

Solution and Explanation

Step 1: Use the energy formula for hydrogen atom.
The energy of the \(n^{\text{th}}\) orbit in hydrogen atom is given by \[ E_n=\frac{-13.6}{n^2}\,\text{eV} \]

Step 2: Find the energy of the ground state.
For the ground state, \[ n=1 \] Therefore, \[ E_1=\frac{-13.6}{1^2} \] \[ E_1=-13.6\,\text{eV} \]

Step 3: Find the energy of the third state.
The third state corresponds to \[ n=3 \] Thus, \[ E_3=\frac{-13.6}{3^2} \] \[ E_3=\frac{-13.6}{9} \] \[ E_3=-1.51\,\text{eV} \]

Step 4: Calculate the excitation energy.
Energy required to excite the electron from ground state to third state is \[ \Delta E=E_3-E_1 \] \[ \Delta E=(-1.51)-(-13.6) \] \[ \Delta E=12.09\,\text{eV} \] \[ \Delta E\approx 12.1\,\text{eV} \]

Step 5: Final conclusion.
Therefore, the required excitation energy is \[ \boxed{12.1\,\text{eV}} \]
Was this answer helpful?
0
0