Radioactive Decay Questions

Radioactivity is a phenomenon that takes place due to nuclear instability. Henry Becquerel discovered radioactivity in 1986. The nucleus of an unstable atom loses energy by emitting radiation.

Radioactive decay is when an unstable atomic nucleus loses energy by radiation. It’s also referred to as nuclear decay, radioactive disintegration, or nuclear disintegration. It is classified into Alpha decay, Beta decay, and Gamma decay.

Alpha decay

A radioactive decay where the unstable atomic nuclei emit a helium nucleus (alpha particle) is known as alpha decay. It is given by the formula:

Where,

• m_i – the initial mass of the nucleus
• m_f – the mass of the nucleus after particles emission
• m_p – the mass of the emitted particle

The best example to explain the alpha decay is the alpha decay of uranium-238.

Beta decay

It is the radioactive decay where a proton is transformed into a neutron or neutron into a proton in the nucleus of the radioactive sample is known as beta decay. The below example explains the beta decay.

There are two beta decay types: beta minus (β^–) and beta plus (β⁺).

Gamma decay

The emission of high-frequency electromagnetic radiation gives out excess energy to stabilise the unstable nucleus called gamma decay.

Radioactive decay states that “The probability per unit time that a nucleus will decay is a constant, independent of time”.

Important Radioactive Decay Questions with Answers

1. What is Transmutation?

Transmutation is the changing of one element into another by radioactive decay, nuclear bombardment, or similar processes.

2. In which decay is the Helium nucleus emitted?

1. Beta-decay
2. Alpha decay
3. Gamma decay
4. Atomic decay

Answer: b) Alpha decay

Explanation: Alpha decay takes place when the unstable atomic nuclei emit a helium nucleus.

3. Who illustrated Fermi’s theory of beta decay?

Enrico Fermi illustrated fermi’s theory of beta decay in 1933.

4. Who created the world’s first nuclear reactor?

1. Albert Einstein
2. Thomas Alva Edison
3. Enrico Fermi
4. Michael Faraday

Answer: c) Enrico Fermi

Explanation: Enrico Fermi created the world’s first nuclear reactor.

4. What are the types of beta decay?

Beta minus decay and Beta plus decay are the two types of beta decay.

5. The decay constant is represented by the symbol _____

1. \(\begin{array}{l}\alpha\end{array} \)
2. \(\begin{array}{l}\lambda\end{array} \)
3. \(\begin{array}{l}\beta\end{array} \)
4. \(\begin{array}{l}\rho\end{array} \)

Answer: b) λ

Explanation: The decay constant is represented by the symbol λ.

6. Which is the unit of radioactivity?

1. Henery
2. Becquerel
3. Rutherford
4. Farad

Answer: c) Rutherford

Explanation: Rutherford is the unit of radioactivity.

7. The probability per unit time that a nucleus will decay is _____ independent of time.

1. Zero always
2. Increasing
3. Decreasing
4. Constant

Answer: d) Constant

Explanation: According to the radioactive decay law, the probability per unit time that a nucleus will decay is constant, independent of time.

8. Uranium-238 shows which type of decay?

1. Beta-decay
2. Alpha decay
3. Gamma decay
4. Atomic decay

Answer: b) Alpha decay

Explanation: Uranium-238 undergoes alpha decay.

9. State true or false: The rate of decay of the nucleus is dependent on temperature and pressure.

1. TRUE
2. FALSE

Answer: b) FALSE

Explanation: The rate of decay of the nucleus is independent of temperature and pressure.

10. High energy photons are emitted in ______

1. Beta-decay
2. Alpha decay
3. Gamma decay
4. Atomic decay

Answer: c) Gamma decay.

Explanation: In the process of gamma decay, high energy photons are emitted.

Practice Questions

1. What is radioactivity?
2. What are the various types of radioactive decay?
3. Give an ideal example to explain alpha decay.
4. Explain the relationship between Curie and Rutherford.
5. Who discovered radioactivity?

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