ETEA / KMU MDCAT (KPK) Physics: Nuclear Physics MCQs

ETEA / KMU MDCAT (KPK) Physics: Nuclear Physics MCQs — sample questions

1. Question 1

   Q1. The nucleus of an atom consists of which particles?

   • A) Protons and electrons
   • B) Protons and neutrons
   • C) Neutrons and electrons
   • D) Protons, neutrons, and electrons

   Answer: Protons and neutrons

   Explanation: Nucleus contains protons and neutrons. Electrons orbit the nucleus.

2. Question 2

   Q2. What is the term for the total number of protons in an atomic nucleus?

   • A) Mass number
   • B) Atomic number
   • C) Neutron number
   • D) Nuclear number

   Answer: Atomic number

   Explanation: Atomic number is the count of protons in the nucleus.

3. Question 3

   Q3. Which type of radiation has the highest penetrating power?

   • A) Alpha particles
   • B) Beta particles
   • C) Gamma rays
   • D) X-rays

   Answer: Gamma rays

   Explanation: Gamma rays are highly penetrating due to their nature as electromagnetic radiation.

4. Question 4

   Q4. The half-life of a radioactive substance is 10 years. What fraction remains after 30 years?

   • A) 1/2
   • B) 1/4
   • C) 1/8
   • D) 1/16

   Answer: 1/8

   Explanation: After 3 half-lives, 1/8 of the substance remains.

5. Question 5

   Q5. In nuclear reactions, what is conserved?

   • A) Mass only
   • B) Energy only
   • C) Both mass and energy
   • D) Neither mass nor energy

   Answer: Both mass and energy

   Explanation: Mass-energy conservation applies in nuclear reactions.

6. Question 6

   Q6. What is the process by which a heavy nucleus splits into two or more lighter nuclei?

   • A) Nuclear fusion
   • B) Radioactive decay
   • C) Nuclear fission
   • D) Nuclear reaction

   Answer: Nuclear fission

   Explanation: Nuclear fission is the splitting of a heavy nucleus.

7. Question 7

   Q7. The binding energy per nucleon is maximum for which nucleus?

   • A) Hydrogen-1
   • B) Helium-4
   • C) Iron-56
   • D) Uranium-238

   Answer: Iron-56

   Explanation: Iron-56 has the highest binding energy per nucleon, making it most stable.

8. Question 8

   Q8. What is the term for the energy required to remove a nucleon from a nucleus?

   • A) Binding energy
   • B) Nuclear energy
   • C) Separation energy
   • D) Ionization energy

   Answer: Separation energy

   Explanation: Separation energy is the energy needed to remove a nucleon.

9. Question 9

   Q9. In a nuclear reactor, what is the function of the moderator?

   • A) To absorb neutrons
   • B) To slow down neutrons
   • C) To cool the reactor
   • D) To control the reaction rate

   Answer: To slow down neutrons

   Explanation: Moderator slows down neutrons to increase the probability of fission.

10. Question 10

    Q10. What is the result of the fusion of two light nuclei?

    • A) A heavier nucleus and energy release
    • B) A lighter nucleus and energy absorption
    • C) No change in nucleus
    • D) Only energy release

    Answer: A heavier nucleus and energy release

    Explanation: Nuclear fusion results in a heavier nucleus and energy release.

11. Question 11

    Q11. The activity of a radioactive sample is measured in which unit?

    • A) Becquerel (Bq)
    • B) Sievert (Sv)
    • C) Gray (Gy)
    • D) Curie (Ci)

    Answer: Becquerel (Bq)

    Explanation: Becquerel is the SI unit of activity, measuring decays per second.

12. Question 12

    Q12. What is the effect of increasing temperature on the rate of radioactive decay?

    • A) Increases the rate
    • B) Decreases the rate
    • C) No effect
    • D) Reverses the decay

    Answer: No effect

    Explanation: Radioactive decay rate is independent of temperature.

13. Question 13

    Q13. Which radiation is most easily stopped by a sheet of paper?

    • A) Alpha particles
    • B) Beta particles
    • C) Gamma rays
    • D) X-rays

    Answer: Alpha particles

    Explanation: Alpha particles are stopped by a sheet of paper due to their large mass and charge.

14. Question 14

    Q14. The mass defect of a nucleus is related to its binding energy by which equation?

    • A) E = mc^2
    • B) E = m/c^2
    • C) E = m*c
    • D) E = m/c

    Answer: E = mc^2

    Explanation: Mass defect is converted into binding energy according to Einstein's equation.

15. Question 15

    Q15. In a nuclear reaction, if the mass of the products is less than the mass of the reactants, what happens to the missing mass?

    • A) It is converted into energy
    • B) It is absorbed by the surroundings
    • C) It is stored in the nucleus
    • D) It disappears

    Answer: It is converted into energy

    Explanation: Missing mass is converted into energy according to E=mc^2.

16. Question 16

    Q16. What is the primary purpose of control rods in a nuclear reactor?

    • A) To slow down neutrons
    • B) To absorb neutrons
    • C) To cool the reactor
    • D) To generate electricity

    Answer: To absorb neutrons

    Explanation: Control rods absorb neutrons to regulate the reaction rate.

17. Question 17

    Q17. The decay constant of a radioactive substance is 0.1 s^-1. What is its half-life?

    • A) 6.93 s
    • B) 0.693 s
    • C) 10 s
    • D) 1 s

    Answer: 6.93 s

    Explanation: Half-life = ln(2)/decay constant = 0.693/0.1 = 6.93 s.

18. Question 18

    Q18. Which of the following is an example of nuclear fusion?

    • A) Uranium-238 decaying into Thorium-234
    • B) Hydrogen nuclei combining to form Helium
    • C) Carbon-14 decaying into Nitrogen-14
    • D) Uranium-235 undergoing fission

    Answer: Hydrogen nuclei combining to form Helium

    Explanation: Hydrogen nuclei fusing to form Helium is an example of nuclear fusion.

19. Question 19

    Q19. The ionizing power is maximum for which type of radiation?

    • A) Alpha particles
    • B) Beta particles
    • C) Gamma rays
    • D) X-rays

    Answer: Alpha particles

    Explanation: Alpha particles have the highest ionizing power due to their charge and mass.

20. Question 20

    Q20. What is the term for the spontaneous emission of radiation from a nucleus?

    • A) Radioactivity
    • B) Nuclear reaction
    • C) Nuclear fission
    • D) Nuclear fusion

    Answer: Radioactivity

    Explanation: Radioactivity is the spontaneous emission of radiation from an unstable nucleus.