16. The existence of dark matter is primarily inferred from its:

15. The energy of the sun is released due to:

14. A worker is preparing to use a radioactive source for an experiment. Which of the following is the PRIMARY reason to maintain a safe distance from the source during use?

13. Food irradiation eliminates bacteria to extend shelf life. Which isotope would be ideal for this purpose?

12. Radiocarbon dating is a technique used to estimate the age of organic materials. What is the approximate maximum age limit for reliable dating using this method?

11. Which of the following is the largest contributor to natural background radiation exposure for most people?

10. The unit for absorbed radiation dose is:

9. The half life of stable isotope is theoretically:

8. A radioactive element with a half-life of two years, the sample remained after 6 years is:

7. During β-decay, the nucleon number:

6. Which of the following decay modes is due to a transition between states of the same nucleus?

5. Cancer treatment involves targeting tumors with radiation. Which type of radiation is most commonly used for its ability to penetrate deep tissues?

4. Beta (β) particles are fast moving:

3. Which of the following is deflected at large angles by electric or magnetic field?

2. Uranium with atomic number 92 has an isotope $^{239}\mathrm{U}$, the number of neutrons in it are:

1. Charge on α-particle is how many times of the charge on proton?