- What is the energy difference between the ground state and the first excited state in a hydrogen atom?
A) 13.6 eV
B) 1.51 eV
C) 3.4 eV
D) 10.2 eV
Answer: A) 13.6 eV.
Explanation: The ground state energy of hydrogen is -13.6 eV, and the first excited state is -3.4 eV, making the energy difference 10.2 eV.
- In the context of the Bohr model, which of the following correctly describes electron transitions?
A) Electrons can transition only by absorbing energy.
B) Electrons can only emit energy when they move to higher energy levels.
C) Electrons can absorb or emit energy during transitions between defined orbits.
D) Electrons do not transition between energy levels.
Answer: C) Electrons can absorb or emit energy during transitions between defined orbits.
Explanation: Electrons can transition to higher levels by absorbing energy and can emit energy when transitioning to lower levels.
- Which of the following elements cannot be accurately described using the Bohr model?
A) Hydrogen
B) Helium
C) Lithium
D) Neon
Answer: D) Neon.
Explanation: The Bohr model is primarily effective for hydrogen-like atoms; more complex atoms like neon involve electron-electron interactions that it cannot account for.
- What is the primary reason for the emission of specific wavelengths in atomic spectra?
A) Random electron movement
B) Different electron masses
C) Quantized energy transitions
D) Variability in atomic size
Answer: C) Quantized energy transitions.
Explanation: Specific wavelengths in atomic spectra arise from quantized energy levels, leading to distinct transitions between those levels.
- What happens to the energy of a photon as its wavelength increases?
A) The energy increases.
B) The energy decreases.
C) The energy remains constant.
D) The energy fluctuates.
Answer: B) The energy decreases.
Explanation: The energy of a photon is inversely related to its wavelength; as the wavelength increases, the energy decreases (E = hc/λ).
- What characteristic of the hydrogen atom’s spectrum is explained by the Bohr model?
A) Continuous spectrum
B) Discrete spectral lines
C) Doppler effect
D) Black body radiation
Answer: B) Discrete spectral lines.
Explanation: The Bohr model explains the discrete lines in the hydrogen spectrum by quantizing electron energy levels.
- Which of the following accurately describes the emission of a photon?
A) It occurs only when an electron is ionized.
B) It is produced when an electron falls to a lower energy state.
C) It happens during electron excitation.
D) It is unrelated to electron transitions.
Answer: B) It is produced when an electron falls to a lower energy state.
Explanation: Emission occurs when an electron drops to a lower energy level, releasing energy in the form of a photon.
- What is the effect of an increase in nuclear charge on the energy levels of an electron?
A) Energy levels become more negative.
B) Energy levels become less negative.
C) Energy levels do not change.
D) Energy levels become undefined.
Answer: B) Energy levels become less negative.
Explanation: An increase in nuclear charge pulls electrons closer, increasing the energy (less negative) of the levels.
- In which situation would an electron be considered in an excited state?
A) When it is in the ground state.
B) When it is at n=1.
C) When it absorbs energy and moves to a higher energy level.
D) When it loses energy and falls to a lower energy level.
Answer: C) When it absorbs energy and moves to a higher energy level.
Explanation: An excited state occurs when an electron gains energy and occupies a higher energy level than the ground state.
- What is the principal quantum number for the third energy level in an atom?
A) 1
B) 2
C) 3
D) 4
Answer: C) 3.
Explanation: The principal quantum number (n) indicates the energy level; for the third energy level, n=3.
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