Class 12 Physics Important Chapter 13 Nuclei Solutions English Medium As Per The New Syllabus to each chapter is provided in the list so that you can easily browse through different chapters ASSEB Class 12 Physics Additional Solutions in English and select need one. NCERT Class 12 Physics Additional Solutions Download PDF. HS 2nd Year Physics Important Solutions.
Class 12 Physics Important Chapter 13 Nuclei
Also, you can read the NCERT book online in these sections Solutions by Expert Teachers as per Central Board of Secondary Education (CBSE) Book guidelines. CBSE Class 12 Physics Additional Question Answer are part of All Subject Solutions. Here we have given HS 2nd Physics Important Solutions English Medium for All Chapters, You can practice these here.
Nuclei
Chapter: 13
| IMPORTANT QUESTION AND ANSWER |
Answer The Following Questions:
1. Name and define, the SI unit for the activity of a given sample of radioactive nuclei.
Ans. Bacquerel. One Bacquerel activity corresponds to ‘one decay’ disintegration per second.
2. Define half life of radioactive material.
Ans. The half life of a radioactive substance is defined as the time during which half the nuclei of the substance disintegrate.
3. Define radioactive decay constant.
Ans. The radioactive decay constant of a substance may be defined as the reciprocal of the time interval during which the number of active nuclei in a given radioactive sample reduces to 1/e times its initial number.
4. What is artificial radioactivity?
Ans. The phenomenon of disintegration of a nuclei (otherwise stable) when it is bombarded with a suitable particle is called artificial radioactivity.
5. State the reason, why heavy water is generally used as a moderator in a nuclear reactor.
Ans. Heavy water contains protons (of mass nearly that of neutrons). Fast moving neutrons undergo elastic collisions with these slow moving neutrons and thus get slowed down. Hence heavy water can be used as a moderator.
6. Define the Curie unit of radioactivity. What do you mean by ‘half-life’?
Ans: The Curie (Ci) is a unit of radioactivity defined as the activity of a sample that emits 3.7 × 10¹⁰ disintegrations per second. It was originally based on the activity of 1 gram of radium-226. This unit helps measure the rate at which radioactive substances decay.
Half-life is the time taken for half of the nuclei in a sample of a radioactive substance to decay. It is a characteristic property of the isotope and gives a measure of the substance’s radioactive stability.
7. Explain mass defect and binding energy.
Ans: Mass defect is the difference between the total mass of the separate protons and neutrons in a nucleus and the actual mass of the nucleus. This “missing” mass is converted into energy when the nucleus is formed.
Binding energy is the energy required to separate a nucleus into its individual protons and neutrons. The mass defect is directly related to the binding energy, as the missing mass is converted into energy that binds the nucleus together. This energy is calculated using Einstein’s mass-energy equivalence E = mc2, where m is the mass defect and c is the speed of light.
8. How much energy should be given to uranium to eject one proton from its nucleus?
Ans: To eject a proton from a uranium-238 nucleus, energy must be supplied to overcome the Coulomb barrier (electrostatic repulsion between the positively charged proton and nucleus). The energy required is roughly equal to the binding energy of the nucleus, which is the energy that binds the protons and neutrons together. The Coulomb barrier also needs to be overcome for the proton to be ejected from the nucleus.
9. How much energy should be given to uranium to eject one proton from its nucleus?
Ans: To eject a proton from Uranium – 238, the energy required will depend on the mass defect and the binding energy per nucleon. The calculation involves converting the mass defect into energy using Einstein’s equation E = mc2 , where mmm is the mass defect. The energy required to overcome the Coulomb repulsion (electrostatic force) must also be taken into account, which requires a high amount of energy, typically in the range of MeV.
10. How was the neutron discovered by James Chadwick?
Ans: Chandwick bombarded boron with α – particles and analyse the interaction of the neutral particles with nitrogen.Nitrogen is chosen because mass of boron and nitrogen are known precisely. Then, conservation of energy and momentum gives mass of neutron.Mass of neutron is found very close to proton.
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