NEET Physics: Atoms and Nuclei Practice Questions
14 free multiple-choice questions on Atoms and Nuclei for NEET Physics, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.
Practice thousands more Atoms and Nuclei questions in the app →Q1. Which of the following statements is a fundamental postulate of the Bohr model?
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Correct answer: C — The angular momentum of the electron is quantized.
The Bohr model postulates that the angular momentum of the electron is quantized, meaning it can only exist in discrete, specific values.
Q2. In the mass-energy relation, if the mass of a system is doubled, its total internal energy will increase by a factor of:
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Correct answer: C — 16
Since E=mc², if m is doubled, the energy E is also doubled. Doubling the mass results in doubling the energy released/stored, assuming c remains constant.
Q3. Which of the following describes the transition of an electron between two stationary energy levels in the Bohr model?
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Correct answer: C — The electron emits a photon.
When an electron moves from a higher energy level to a lower energy level, it releases the energy difference in the form of electromagnetic radiation (a photon).
Q4. In the Bohr model of the hydrogen atom, the energy of an electron in the n⁽th) stationary orbit is proportional to which expression?
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Correct answer: A — 1/n²
The energy of an electron in the n⁽th) orbit of a hydrogen atom is given by the formula Eₙ = -R_H/n², where R_H is the Rydberg constant. Thus, the energy is inversely proportional to the square of the principal quantum number (Eₙ ∝ 1/n²).
Q5. For the hydrogen atom, the radius of the n-th orbit in the Bohr model is proportional to which term?
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Correct answer: B — 1/n²
The radius of the n-th orbit is given by rₙ ∝ n², where n is the principal quantum number.
Q6. What is the term used to describe the minimum possible energy state of an electron in an atomic system?
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Correct answer: D — Ground state.
The minimum possible energy state of an electron in an atom is defined as the ground state.
Q7. The radius of the nth orbit in the Bohr model is inversely proportional to which term?
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Correct answer: C — The principal quantum number n.
The radius of the orbit (rₙ) is proportional to n², meaning it is inversely related to the quantization number n in a conceptual sense of determining the size of the orbit.
Q8. The energy released during a nuclear fission reaction is primarily due to:
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Correct answer: B — Change in the binding energy of the nucleons
Energy release in fission is due to the increased binding energy of the resulting, more stable, lighter nuclei.
Q9. The Bohr model successfully explained the stability of the atom primarily by introducing which concept?
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Correct answer: A — Quantization of angular momentum.
The quantization of angular momentum ensures that electrons remain in stable, well-defined orbits, thus explaining the stability of the atom in this model.
Q10. Which term describes the nucleus of an atom that has a definite number of protons but a variable number of neutrons?
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Correct answer: A — Isotope
An isotope is a variant of an element that has the same number of protons but a different number of neutrons.
Q11. The mass defect (Δm) in a nuclear reaction is defined as the difference between the mass of the reactants and the mass of the products. This mass defect is converted into energy according to which principle?
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Correct answer: B — Conservation of Mass-Energy
According to Einstein's mass-energy relation (E=mc²), the difference in mass (Δm) results in a corresponding energy release.
Q12. In the context of mass-energy equivalence, the constant c² (speed of light squared) has units of:
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Correct answer: B — Joules per kilogram.
Since E=mc², c² must have units such that m × c² = E (Joules). Therefore, the units of c² are Joules per kilogram (J/kg).
Q13. What is the primary postulate of the Bohr model concerning the electron's motion in an orbit?
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Correct answer: B — The electron has only discrete, stationary orbits
The core postulate of the Bohr model is that the electron exists only in specific, quantized, stationary orbits, and these orbits are allowed states.
Q14. Which quantity is considered the actual mass of a nucleus, accounting for the binding energy within it?
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Correct answer: C — The mass defect
The actual mass of a nucleus is its rest mass, which is smaller than the sum of the masses of its individual nucleons because of the energy locked in as binding energy.
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