Physics ยท Chemistry

Radioactivity and Nuclear Physics

519 Questions

Radioactivity and nuclear physics encompass the study of radioactive decay processes, neutron to proton ratios, and nuclear medicine. Questions cover various detection mechanisms, including scintillation counters and neutrino telescopes. These concepts are frequently tested in advanced science and civil services examinations.

Radioactive decayNuclear medicineParticle detectionNeutrino telescopesCosmic ray detection

Radioactivity and Nuclear Physics Questions

Multiple choice

Strontium-90 is one of the isotopes which results from a nuclear fall out. Which of the following facts about it are true?

  1. It tends to deposit in bones and bone marrow.
  2. It has a half life of 29 years.
  3. It can cause thyroid related problems.
  4. It can cause leukemia.
  5. Potassium iodide can block it from adversely affecting human body.

  1. 1, 2 and 3

  2. 1, 2, 3 and 4

  3. 2, 3 and 5

  4. 1, 2 and 4
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Statements 3 and 5 are true with respect to another radioactive element, Iodine-129.

Multiple choice

Which of the following is a condition for existence of a radioactive element?

  1. The number of protons and neutrons are nearly equal.

  2. The number of protons exceeds the number of neutrons.

  3. The number of neutrons exceeds the number of protons.

  4. The number of protons exceeds the number of electrons.

  5. The number of electrons exceeds the number of neutrons.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When the number of neutrons exceeds the number of protons in a nucleus, it becomes unstable or radioactive.

Multiple choice

Which of the following is a result of an alpha emission from a radioactive element?

  1. The atomic number of the daughter element is increaseed by 2.

  2. The atomic number of the daughter element is decreased by 2.

  3. The mass number of the daughter element is increased by 4.

  4. Atomic number of daughter element is increased by 2, and mass number is increased by 4.

  5. Atomic number of daughter element is decreased by 2, and mass number is decreased by 4.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

When an alpha particle comes out of the nucleus of a radioactive element, the atomic number and the mass number decrease by 2 and 4, respectively.

Multiple choice

Which of the following is not correct for gamma radiations?

(a) Gamma radiations occur when the parent nucleus is in a state of excitation. (b) They are the electromagnetic waves. (c) Their ionising power is very high. (d) They affect a photographic plate. (e) They do not cause fluorescence.

  1. Only (a)

  2. Only (b)

  3. Both (a) and (c)

  4. Both (b) and (d)

  5. Both (c) and (e)
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The ionising power of gamma radiations is very low as it not composed of charged particles like alpha and beta particles. They cause fluorescence when they are incident on a fluorescent material.

Multiple choice

Which of the following helps in explaining the phenomenon of radioactivity?

  1. Law of conservation of mass

  2. Law of conservation of charge

  3. Law of conservation of mass and charge

  4. Law of constant and multiple proportion

  5. Law of conservation of charge and constant proportion
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Both the mass and charge remain conserved during disintegration of a radioactive element.

Multiple choice

What of the following is not correct about background radiation?

  1. They are radiations to which we all are exposed even in the absence of visible radioactive sources.

  2. Radium, K-40 and C-14 are some of the sources of these radiations.

  3. They cause serious biological damage to us.

  4. Gamma radiations come from the radioactive rocks in the earth's crust.

  5. They do not exceed the maximum permissible level for human safety.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The background radiations do not cause serious biological damage to us because they do not exceed the maximum permissible level for human safety.

Multiple choice

Which rays are produced by the nucleus of radioactive substances?

  1. Infrared rays

  2. Ultraviolet rays

  3. Gamma rays

  4. Micro waves
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Gamma rays are produced by nuclear processes in radioactive substances, specifically from the nucleus during radioactive decay or nuclear reactions. Infrared and ultraviolet rays come from electronic transitions in atoms. Microwaves are generated by electronic devices, not nuclear processes.

Multiple choice

Which of the following are high energy electromagnetic radiations?

  1. Gamma rays

  2. Cosmic rays

  3. Beta rays

  4. X-rays
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Gamma rays have the highest energy in the electromagnetic spectrum. They are produced by nuclear processes and have the shortest wavelengths. While X-rays are also high-energy, gamma rays are even more energetic. Cosmic rays are primarily high-energy protons, not electromagnetic radiation. Beta rays are electrons, not electromagnetic waves.

Multiple choice

If a U-238 nucleus splits into two identical parts, the two nuclei so produced will be

  1. radioactive

  2. stable

  3. isotopes

  4. isobars
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

U-238 has 92 protons and 146 neutrons. If it splits into two IDENTICAL nuclei, each gets 46 protons and 73 neutrons, forming Pd-119. Pd-119 has a neutron-to-proton ratio of 1.59, far above the stability line of ~1.3 for medium-mass nuclei. This extreme neutron excess makes it highly unstable, requiring radioactive decay to reach stability. Option B (stable) is wrong because equal fission of a heavy nucleus always produces neutron-rich fragments. Option C (isotopes) is incorrect - the two fragments ARE identical isotopes of Pd-119. Option D (isobars) is wrong because isobars have different atomic numbers, but these fragments both have Z=46.

Multiple choice

The term ' radioactivity' was first used by

  1. Henri Becquerel

  2. Marie Curie

  3. Rutherford

  4. De broglie
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Marie Curie coined the term 'radioactivity' in 1898 to describe the spontaneous emission of radiation from atomic nuclei. Henri Becquerel discovered radioactivity (through uranium), but Curie named it. Rutherford contributed to nuclear physics understanding. De Broglie proposed wave-particle duality.