- In the Bohr model, what happens to an electron when it absorbs a photon?
A) It loses energy.
B) It moves to a higher energy level.
C) It becomes ionized.
D) It spirals into the nucleus.
Answer: B) It moves to a higher energy level.
Explanation: Absorbing a photon provides energy, allowing the electron to transition to a higher energy state.
- Which of the following does not contribute to the Bohr model’s success?
A) It explains the line spectrum of hydrogen.
B) It applies to all elements equally well.
C) It incorporates quantization.
D) It uses classical mechanics effectively.
Answer: B) It applies to all elements equally well.
Explanation: The Bohr model is most accurate for hydrogen-like atoms and does not effectively apply to more complex atoms.
- What type of radiation corresponds to the transition from n=5 to n=2 in a hydrogen atom?
A) Ultraviolet radiation
B) Visible light
C) Infrared radiation
D) X-rays
Answer: A) Ultraviolet radiation.
Explanation: The transition from n=5 to n=2 in hydrogen emits ultraviolet radiation, which is part of the Lyman series.
- How many total orbitals are in the n=3 energy level?
A) 1
B) 3
C) 5
D) 9
Answer: C) 9.
- What is the maximum number of electrons that can occupy the n=4 energy level?
A) 2
B) 8
C) 18
D) 32
Answer: C) 32.
- Which phenomenon explains the splitting of spectral lines in a magnetic field?
A) Doppler effect
B) Stark effect
C) Zeeman effect
D) Photoelectric effect
Answer: C) Zeeman effect.
Explanation: The Zeeman effect refers to the splitting of spectral lines due to the presence of a magnetic field.
- In the hydrogen atom, what does a transition from n=4 to n=2 correspond to?
A) Emission of infrared light
B) Absorption of visible light
C) Emission of visible light
D) Absorption of ultraviolet light
Answer: C) Emission of visible light.
Explanation: The transition from n=4 to n=2 emits visible light, part of the Balmer series.
- What does the magnetic quantum number (m) indicate?
A) The energy of the electron
B) The shape of the orbital
C) The orientation of the orbital
D) The spin of the electron
Answer: C) The orientation of the orbital.
Explanation: The magnetic quantum number specifies the orientation of orbitals in a given subshell.
- Which concept describes the maximum number of electrons in a subshell?
A) Aufbau principle
B) Pauli exclusion principle
C) Hund’s rule
D) Quantum mechanical model
Answer: B) Pauli exclusion principle.
Explanation: The Pauli exclusion principle states that no two electrons in an atom can have the same set of quantum numbers, determining the maximum occupancy in orbitals.
- What energy level corresponds to the first ionization energy of hydrogen?
A) n=1
B) n=2
C) n=3
D) n=4
Answer: A) n=1.
Explanation: The first ionization energy corresponds to removing the electron from the ground state, which is at n=1.
- In which situation would an electron in an atom experience the greatest repulsion?
A) When it is closest to the nucleus.
B) When it is in the same orbital as another electron.
C) When it is in a higher energy level.
D) When it is in a completely filled subshell.
Answer: B) When it is in the same orbital as another electron.
Explanation: Electrons repel each other due to their negative charge, and the greatest repulsion occurs when they occupy the same orbital.
- How does the Bohr model address the stability of electron orbits?
A) By assuming electrons are stationary.
B) By proposing that electrons can only exist in quantized orbits.
C) By using classical mechanics.
D) By disregarding electron energy levels.
Answer: B) By proposing that electrons can only exist in quantized orbits.
Explanation: The Bohr model suggests that stability arises from electrons occupying fixed, quantized energy levels without radiating energy.
- Which series in the hydrogen spectrum results in emissions visible to the human eye?
A) Lyman series
B) Balmer series
C) Paschen series
D) Brackett series
Answer: B) Balmer series.
Explanation: The Balmer series corresponds to visible light emissions when electrons transition to the n=2 level.
- What is the primary limitation of the Bohr model?
A) It explains multi-electron atoms well.
B) It cannot predict the fine structure of spectral lines.
C) It applies to all elements accurately.
D) It ignores electron spin.
Answer: B) It cannot predict the fine structure of spectral lines.
Explanation: The Bohr model fails to account for fine structure and complexities in multi-electron systems.
- Which quantum number represents the size of an orbital?
A) Principal quantum number (n)
B) Azimuthal quantum number (l)
C) Magnetic quantum number (m)
D) Spin quantum number (s)
Answer: A) Principal quantum number (n).
Explanation: The principal quantum number (n) determines the energy level and size of the orbital.
- What is the primary factor that determines the color of light emitted by an electron transition?
A) The speed of the electron
B) The energy difference between levels
C) The type of atom
D) The temperature of the atom
Answer: B) The energy difference between levels.
Explanation: The color of emitted light corresponds to the energy difference between the two levels involved in the transition.
- In the context of the Bohr model, what does a negative energy value indicate?
A) The atom is unstable.
B) The electron is bound to the nucleus.
C) The electron is free.
D) The atom has lost an electron.
Answer: B) The electron is bound to the nucleus.
Explanation: Negative energy values indicate that the electron is in a bound state within the atom, meaning it requires energy to escape.
- What is the shape of an s orbital?
A) Dumbbell
B) Spherical
C) Double dumbbell
D) Linear
Answer: B) Spherical.
Explanation: An s orbital has a spherical shape, surrounding the nucleus evenly in all directions.
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