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An electron in a hydrogen atom is excite...

An electron in a hydrogen atom is excited from the ground state to the n = 4 state. Predict which of the following statements are true or false :
(i) `n = 4` is the first excited state.
(ii) It takes more energy to ionize (remove) the electron from n = 14 than in the ground state.
(iii) The wavelength of light emitted when the electron drops from `n = 4` to `n = 2` is longer than that from `n = 4` to `n = 1`.
(iv) The wavelength which the atom absorbs in going from `n = 1` to `n = 4` is the same as emitted when it goes from `n = 4` to `n = 1`.
(v) The electron is farther from the nucleus (on average) in n = 4 than in the ground state.

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The correct Answer is:
To determine the truth value of each statement regarding the hydrogen atom when an electron is excited from the ground state to the n = 4 state, we will analyze each statement one by one. ### Solution Steps: 1. **Statement (i): `n = 4` is the first excited state.** - The ground state of hydrogen corresponds to n = 1. The first excited state is n = 2, the second excited state is n = 3, and so on. Therefore, n = 4 is actually the third excited state. - **Conclusion**: **False** 2. **Statement (ii): It takes more energy to ionize (remove) the electron from n = 14 than in the ground state.** - The energy of an electron in a hydrogen atom is given by the formula: \[ E_n = -\frac{13.6 \, Z^2}{n^2} \text{ eV} \] For n = 1 (ground state), the energy is -13.6 eV. For n = 14, the energy is: \[ E_{14} = -\frac{13.6}{14^2} \approx -0.0693 \text{ eV} \] Ionization energy from n = 1 is 13.6 eV, while from n = 14 it is approximately 0.0693 eV. Thus, it takes less energy to ionize from n = 14 than from the ground state. - **Conclusion**: **False** 3. **Statement (iii): The wavelength of light emitted when the electron drops from `n = 4` to `n = 2` is longer than that from `n = 4` to `n = 1`.** - The energy difference for transitions is given by: \[ \Delta E = E_{n_1} - E_{n_2} \] For n = 4 to n = 2: \[ \Delta E_{4 \to 2} = E_2 - E_4 \] For n = 4 to n = 1: \[ \Delta E_{4 \to 1} = E_1 - E_4 \] Since the transition from n = 4 to n = 1 involves a larger energy difference than from n = 4 to n = 2, the wavelength emitted (which is inversely proportional to energy) will be shorter for n = 4 to n = 1. - **Conclusion**: **False** 4. **Statement (iv): The wavelength which the atom absorbs in going from `n = 1` to `n = 4` is the same as emitted when it goes from `n = 4` to `n = 1`.** - The energy absorbed when moving from n = 1 to n = 4 is equal to the energy emitted when moving from n = 4 to n = 1. Thus, the wavelengths will be the same because they correspond to the same energy change. - **Conclusion**: **True** 5. **Statement (v): The electron is farther from the nucleus (on average) in n = 4 than in the ground state.** - The radius of the nth orbit in a hydrogen atom is given by: \[ r_n = 0.529 \, \frac{n^2}{Z} \text{ angstroms} \] Since the radius is proportional to \( n^2 \), the electron in n = 4 will be farther from the nucleus than in n = 1. - **Conclusion**: **True** ### Final Answers: - (i) False - (ii) False - (iii) False - (iv) True - (v) True
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