ROUTERA

Nuclei

Class 12th Physics Chapter Case Study

Case Study 1: Composition of the Nucleus

The atomic nucleus is composed of protons and neutrons, collectively known as nucleons. The number of protons determines the element's identity, while the number of neutrons affects the stability of the nucleus. Different isotopes of an element have the same number of protons but different numbers of neutrons.

Questions:

  1. What are the particles that make up the nucleus?
    • a) Electrons and protons
    • b) Protons and neutrons
    • c) Neutrons and positrons
    • d) Electrons and neutrons
  2. What determines the identity of an element?
    • a) Number of neutrons
    • b) Mass number
    • c) Number of protons
    • d) Total number of nucleons
  3. Isotopes of an element differ in the number of:
    • a) Protons
    • b) Electrons
    • c) Neutrons
    • d) Nucleons
  4. Which of the following statements is true regarding isotopes?
    • a) They have different atomic numbers.
    • b) They have the same mass number.
    • c) They exhibit different chemical properties.
    • d) They have the same number of neutrons.

Answers:

  1. b) Protons and neutrons
  2. c) Number of protons
  3. c) Neutrons
  4. a) They have different atomic numbers.

Case Study 2: Nuclear Forces

Nuclear forces are the strong forces that hold the protons and neutrons together in the nucleus. These forces are short-range but are significantly stronger than the electromagnetic repulsion between protons. The balance between the nuclear forces and the repulsive forces determines the stability of the nucleus.

Questions:

  1. What type of force holds the nucleons together in the nucleus?
    • a) Gravitational force
    • b) Electromagnetic force
    • c) Strong nuclear force
    • d) Weak nuclear force
  2. The electromagnetic repulsion occurs between which particles in the nucleus?
    • a) Neutrons
    • b) Protons
    • c) Electrons
    • d) Nucleons
  3. The stability of a nucleus is determined by the balance between:
    • a) Gravitational forces and electromagnetic forces
    • b) Strong nuclear forces and electromagnetic forces
    • c) Weak nuclear forces and gravitational forces
    • d) Strong nuclear forces and weak nuclear forces
  4. If a nucleus has too many protons, it is likely to be:
    • a) Stable
    • b) Unstable and radioactive
    • c) Neutral
    • d) Non-radioactive

Answers:

  1. c) Strong nuclear force
  2. b) Protons
  3. b) Strong nuclear forces and electromagnetic forces
  4. b) Unstable and radioactive

Case Study 3: Radioactive Decay

Radioactive decay is a process by which an unstable atomic nucleus loses energy by emitting radiation. This can occur in several forms, including alpha decay, beta decay, and gamma decay. The decay process transforms the original element into a different element or isotope.

Questions:

  1. What is radioactive decay?
    • a) The transformation of an atom into a more stable state by emitting radiation
    • b) The process of fusion in stars
    • c) The splitting of an atom into smaller parts
    • d) The combination of two atoms to form a new atom
  2. Which type of decay involves the emission of helium nuclei?
    • a) Beta decay
    • b) Alpha decay
    • c) Gamma decay
    • d) Positron emission
  3. Beta decay results in the conversion of a:
    • a) Proton to a neutron
    • b) Neutron to a proton
    • c) Helium nucleus to a carbon nucleus
    • d) Proton to an electron
  4. Which decay process does not change the mass number of the nucleus?
    • a) Alpha decay
    • b) Beta decay
    • c) Gamma decay
    • d) All of the above

Answers:

  1. a) The transformation of an atom into a more stable state by emitting radiation
  2. b) Alpha decay
  3. b) Neutron to a proton
  4. c) Gamma decay

Case Study 4: Nuclear Fission

Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei, along with the release of energy. This process can be induced by bombarding the nucleus with neutrons and is the principle behind nuclear reactors and atomic bombs.

Questions:

  1. What is nuclear fission?
    • a) The process of splitting a nucleus into smaller parts
    • b) The fusion of two light nuclei into a heavier nucleus
    • c) The decay of a radioactive nucleus
    • d) The emission of gamma rays from a nucleus
  2. Which element is commonly used as fuel in nuclear reactors?
    • a) Uranium-235
    • b) Carbon-12
    • c) Helium-4
    • d) Iron-56
  3. What is released as a result of nuclear fission?
    • a) Heat and light
    • b) Neutrons and energy
    • c) Electrons and protons
    • d) Only protons
  4. The chain reaction in nuclear fission is caused by:
    • a) The absorption of photons
    • b) The release of neutrons that cause further fission
    • c) The fusion of two nuclei
    • d) The decay of beta particles

Answers:

  1. a) The process of splitting a nucleus into smaller parts
  2. a) Uranium-235
  3. b) Neutrons and energy
  4. b) The release of neutrons that cause further fission

Case Study 5: Nuclear Fusion

Nuclear fusion is a process where two light atomic nuclei combine to form a heavier nucleus, releasing energy in the process. This is the reaction that powers the sun and other stars. Fusion has the potential to be a cleaner and more sustainable energy source compared to fission.

Questions:

  1. What is nuclear fusion?
    • a) The splitting of a heavy nucleus into smaller nuclei
    • b) The combination of two light nuclei to form a heavier nucleus
    • c) The emission of beta particles from a nucleus
    • d) The decay of radioactive isotopes
  2. Which of the following reactions is an example of nuclear fusion?
    • a) Deuterium + Tritium → Helium + Neutron
    • b) Uranium-235 + Neutron → Barium + Krypton + Neutrons
    • c) Carbon-14 → Nitrogen-14 + Electron
    • d) Radium-226 → Radon-222 + Alpha particle
  3. Which condition is necessary for nuclear fusion to occur?
    • a) High temperatures and pressures
    • b) Low temperatures
    • c) Zero pressure
    • d) Absence of neutrons
  4. The energy produced by nuclear fusion is primarily due to:
    • a) The binding energy of the nucleus
    • b) The kinetic energy of electrons
    • c) The gravitational potential energy
    • d) The energy released by radioactive decay

Answers:

  1. b) The combination of two light nuclei to form a heavier nucleus
  2. a) Deuterium + Tritium → Helium + Neutron
  3. a) High temperatures and pressures
  4. a) The binding energy of the nucleus