47 practice MCQs on radioactivity, nuclear reactions, half-life, fission, fusion and binding energy. Every question has the correct answer and an explanation.
Start free — 20 questionsNuclear Physics is part of the MDCAT Physics syllabus. This page collects Nuclear Physics MCQs in the style of past MDCAT papers — below are 12 of them with answers and explanations, and the full set of 47 questions is in the HighYield MDCAT QBank.
This chapter covers: radioactivity, nuclear reactions, half-life, fission, fusion and binding energy.
Correct answer: A. Neon
In a Helium-Neon laser, helium atoms are excited first and transfer energy to neon atoms via collisions, but it is the neon atoms that achieve population inversion and emit the laser radiation upon stimulated transition to a lower energy level.
Correct answer: A. Beta particles
When a neutron transforms into a proton within the nucleus, a beta particle (electron) is emitted, along with an antineutrino.
Correct answer: A. -4
Alpha emission reduces the mass (nucleon) number by 4, while beta and gamma emission do not change the mass number, giving a total change of -4 for this combined decay.
Correct answer: B. Gamma
Gamma rays have the strongest penetration power among alpha, beta and gamma radiation, since they are uncharged, high-energy electromagnetic photons that interact weakly with matter.
Correct answer: C. Beta
The transformation of Th-234 to Pa-234, with atomic number increasing by 1 while mass number stays the same, indicates the emission of a beta particle.
Correct answer: C. ‘Z’ decreases by 4 and ‘A’ decreases by 8
Emission of two alpha particles reduces the atomic number (Z) by 4 (2 per alpha) and the mass number (A) by 8 (4 per alpha).
Correct answer: B. Plasma Blood Volume
Sodium-24, with a half-life of about 15 hours, is used medically to estimate blood plasma volume by tracer dilution.
Correct answer: D. 1 Gray (Copyrights Protected MCAT Preparations 2017 – ARK)
The absorption of radiation energy at a rate of one joule per kilogram of absorbing material defines the unit of absorbed dose called the gray.
Correct answer: B. Cobalt 60
Radiotherapy is often done with gamma rays emitted from Cobalt-60 sources. Cobalt-60 is a synthetic radioactive isotope with a half-life of about 5.26 years. It decays by emitting beta particles and gamma rays, and these gamma rays are used in radiotherapy to treat various medical conditions, particularly cancer.
Correct answer: C. 0.00000187 m
Given the options provided, 0.00000187 m (which is 1.87 µm) represents the longest wavelength of radiation in the Paschen series. The other option, 187000000 m, is an exceedingly large wavelength that is not applicable to the Paschen series or any other typical electromagnetic radiation observed in atomic transitions.
Correct answer: C. 11g
To find the remaining amount of a radioactive element after a certain number of half-lives, you can use the formula: Remaining Quantity = Initial Quantity × (1/2)^(number of half-lives). Here, the initial quantity is 88g and the number of half-lives is 3. Therefore, Remaining Quantity = 88g × (1/2)^3 = 88g × (1/8) = 11g. Thus, after 3 half-lives, 11g of the element remains.Option A (8g) is incorrect because it suggests an even more significant decay than calculated. Option B (10g) underestimates the remaining amount after 3 half-lives. Option D (44g) incorrectly assumes only one half-life has occurred, which is not the case.
Correct answer: D. (7/2) min
N(t) = No × (1/2)^(t/T)N(t) = remaining amount after time tNo = initial amountt = time elapsed (14 min)T = half-life (unknown)Given:N(t) = 1/16 N0 (remaining amount after 14 min)(1/16) = (1/2)^(14/T)(1/2)^4 = (1/2)^(14/T)Comparing the exponents, we get:4 = 14/TSolving for T, we get:T = 14/4T = 7/2T = 3.5 min
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