Chapter 6: Nuclear Physics — Online MCQ Test
SCIENCE · CLASS 10th · Tamil Nadu State Board
Practice Chapter 6: Nuclear Physics with a free chapter-wise online MCQ test.
This chapter covers: Focusing on radioactivity this chapter covers natural and artificial radioactivity alpha beta gamma decay and nuclear reactions. Students study nuclear fission nuclear fusion radia....
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Chapter 6: Nuclear Physics — Important Questions & Answers
What is radioactivity?
- A. Spontaneous emission of radiations from unstable atomic nuclei
- B. Emission of light from heated metals
- C. Flow of electrons through a conductor
- D. Splitting of molecules by electricity
Answer: A. Spontaneous emission of radiations from unstable atomic nuclei
Radioactivity is the spontaneous disintegration of unstable nuclei with emission of alpha, beta or gamma radiations.
Radioactivity is the spontaneous disintegration of unstable nuclei with emission of alpha, beta or gamma radiations.
An alpha particle is identical to the nucleus of which atom?
- A. Hydrogen
- B. Helium
- C. Lithium
- D. Carbon
Answer: B. Helium
An alpha particle consists of 2 protons and 2 neutrons, which is the nucleus of a helium atom.
An alpha particle consists of 2 protons and 2 neutrons, which is the nucleus of a helium atom.
Which of the following radiations has no mass and no charge?
- A. Alpha rays
- B. Beta rays
- C. Gamma rays
- D. Canal rays
Answer: C. Gamma rays
Gamma rays are electromagnetic radiations, so they have no mass and no electric charge.
Gamma rays are electromagnetic radiations, so they have no mass and no electric charge.
In a nuclear reactor, control rods are commonly made of ________.
- A. Cadmium or boron
- B. Aluminium or copper
- C. Graphite or heavy water
- D. Uranium or plutonium
Answer: A. Cadmium or boron
Cadmium and boron absorb excess neutrons and help control the rate of nuclear fission in a reactor.
Cadmium and boron absorb excess neutrons and help control the rate of nuclear fission in a reactor.
During beta decay, what happens to the atomic number and mass number of the parent nucleus?
- A. Atomic number decreases by 2, mass number decreases by 4
- B. Atomic number increases by 1, mass number remains unchanged
- C. Atomic number remains unchanged, mass number decreases by 1
- D. Atomic number decreases by 1, mass number increases by 1
Answer: B. Atomic number increases by 1, mass number remains unchanged
In beta decay, a neutron changes into a proton and emits a beta particle, so atomic number increases by 1 while mass number remains the same.
In beta decay, a neutron changes into a proton and emits a beta particle, so atomic number increases by 1 while mass number remains the same.
When uranium-238 emits an alpha particle, the daughter nucleus formed is ________.
- A. Thorium-234
- B. Protactinium-238
- C. Radium-234
- D. Uranium-234
Answer: A. Thorium-234
In alpha decay, mass number decreases by 4 and atomic number decreases by 2. Thus uranium-238 becomes thorium-234.
In alpha decay, mass number decreases by 4 and atomic number decreases by 2. Thus uranium-238 becomes thorium-234.
Which of the following statements is NOT correct about radioactive radiations?
- A. Alpha rays have low penetrating power
- B. Beta rays are more penetrating than alpha rays
- C. Gamma rays are not affected by electric or magnetic fields
- D. Alpha rays are negatively charged particles
Answer: D. Alpha rays are negatively charged particles
Alpha rays are positively charged particles, not negatively charged. Beta rays are negatively charged electrons.
Alpha rays are positively charged particles, not negatively charged. Beta rays are negatively charged electrons.
A radioactive radiation is deflected towards the negative plate in an electric field. Which radiation is it most likely to be?
- A. Alpha radiation
- B. Beta radiation
- C. Gamma radiation
- D. X-radiation
Answer: A. Alpha radiation
Alpha particles are positively charged, so they are attracted towards the negative plate in an electric field.
Alpha particles are positively charged, so they are attracted towards the negative plate in an electric field.
Complete the nuclear reaction: ²³⁵₉₂U + ¹₀n → ¹⁴¹₅₆Ba + ⁹²₃₆Kr + x ¹₀n + energy. What is the value of x?
- A. 1
- B. 2
- C. 3
- D. 4
Answer: C. 3
Mass numbers must balance: 235 + 1 = 141 + 92 + x, so x = 3. Atomic numbers are also balanced.
Mass numbers must balance: 235 + 1 = 141 + 92 + x, so x = 3. Atomic numbers are also balanced.
A radioactive sample has 80 g initially. After 30 years, only 10 g remains undecayed. What is its half-life?
- A. 5 years
- B. 10 years
- C. 15 years
- D. 30 years
Answer: B. 10 years
80 g becomes 40 g, then 20 g, then 10 g in three half-lives. Therefore, 3 half-lives = 30 years, so one half-life = 10 years.
80 g becomes 40 g, then 20 g, then 10 g in three half-lives. Therefore, 3 half-lives = 30 years, so one half-life = 10 years.