{"id":57386,"date":"2022-01-24T10:09:03","date_gmt":"2022-01-24T04:39:03","guid":{"rendered":"https:\/\/infinitylearn.com\/surge\/?p=57386"},"modified":"2024-07-10T14:57:01","modified_gmt":"2024-07-10T09:27:01","slug":"ncert-exemplar-for-class-12-physics-chapter-13-nuclei","status":"publish","type":"post","link":"https:\/\/infinitylearn.com\/surge\/study-materials\/ncert-exemplar-solutions\/class-12\/physics\/chapter-13-nuclei\/","title":{"rendered":"NCERT Exemplar for Class 12 Physics Chapter 13 &#8211; Nuclei"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_37 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" style=\"display: none;\"><label for=\"item\" aria-label=\"Table of Content\"><span style=\"display: flex;align-items: center;width: 35px;height: 30px;justify-content: center;\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/label><input type=\"checkbox\" id=\"item\"><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1' style='display:block'><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/infinitylearn.com\/surge\/study-materials\/ncert-exemplar-solutions\/class-12\/physics\/chapter-13-nuclei\/#Download_the_PDF_of_the_NCERT_Exemplar_Class_12_Physics_Chapter_13_Nuclei\" title=\"Download the PDF of the NCERT Exemplar Class 12 Physics Chapter 13 Nuclei\">Download the PDF of the NCERT Exemplar Class 12 Physics Chapter 13 Nuclei<\/a><ul class='ez-toc-list-level-3'><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/infinitylearn.com\/surge\/study-materials\/ncert-exemplar-solutions\/class-12\/physics\/chapter-13-nuclei\/#Access_Solutions_to_the_NCERT_Exemplar_Class_12_Physics_Chapter_13\" title=\"Access Solutions to the NCERT Exemplar Class 12 Physics Chapter 13\">Access Solutions to the NCERT Exemplar Class 12 Physics Chapter 13<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/infinitylearn.com\/surge\/study-materials\/ncert-exemplar-solutions\/class-12\/physics\/chapter-13-nuclei\/#Short_Answer_Types\" title=\"Short Answer Types\">Short Answer Types<\/a><ul class='ez-toc-list-level-4'><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/infinitylearn.com\/surge\/study-materials\/ncert-exemplar-solutions\/class-12\/physics\/chapter-13-nuclei\/#More_Resources_for_Class_12\" title=\"More Resources for Class 12\">More Resources for Class 12<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/infinitylearn.com\/surge\/study-materials\/ncert-exemplar-solutions\/class-12\/physics\/chapter-13-nuclei\/#Topics_Discussed_in_Class_12_Chapter_13_Nuclei\" title=\"Topics Discussed in Class 12 Chapter 13 Nuclei\">Topics Discussed in Class 12 Chapter 13 Nuclei<\/a><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n<p>The <a href=\"https:\/\/infinitylearn.com\/surge\/study-materials\/ncert-exemplar-solutions\/class-12\/physics\/\"><strong>NCERT Exemplar class 12 physics<\/strong><\/a> solutions for Chapter 13 Nuclei are meticulously prepared by the highly experienced faculty at Infinity Learn. These solutions are designed to assist students in their board exam preparation, aligning with the <a href=\"https:\/\/infinitylearn.com\/surge\/cbse\/cbse-syllabus\/\"><strong>CBSE syllabus<\/strong><\/a> and exam patterns. Solving these exemplar questions helps students clear their doubts and gain a thorough understanding of the chapter on Nuclei.<\/p>\n<p>This exemplar solution page includes answers to the questions from the <a href=\"https:\/\/infinitylearn.com\/surge\/study-materials\/ncert-books\/\"><strong>NCERT book<\/strong><\/a>, supplemented with extra questions curated by our subject experts. It also incorporates questions from previous years\u2019 question papers, sample papers, and additional resources. Utilizing these solutions enables students to grasp the core concepts effectively and achieve high scores in their board exams.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Download_the_PDF_of_the_NCERT_Exemplar_Class_12_Physics_Chapter_13_Nuclei\"><\/span>Download the PDF of the NCERT Exemplar Class 12 Physics Chapter 13 Nuclei<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-size: 12pt;\">\n\t\t<div class=\"download-pdf-container\">\n\t\t\t<span class=\"title\">Do you need help with your Homework? 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href=\"\/surge\/?pdfemb-serveurl=https%3A%2F%2Finfinitylearn.com%2Fsurge%2Fwp-content%2Fuploads%2Fsecurepdfs%2F2022%2F01%2FClass12_Physics_Chapter13DE-56.pdf\" class=\"pdfemb-viewer\" style=\"\" data-width=\"max\" data-height=\"max\" data-mobile-width=\"0\"  data-scrollbar=\"both\" data-download=\"off\" data-tracking=\"on\" data-newwindow=\"on\" data-pagetextbox=\"off\" data-scrolltotop=\"on\" data-startzoom=\"100\" data-startfpzoom=\"100\" data-download-nonce=\"f98acbbbf4\" data-disablerightclick=\"on\" data-toolbar=\"top\" data-toolbar-fixed=\"on\">Class12_Physics_Chapter13(DE-56)<br\/><\/a><\/span><\/p>\n<h3><span class=\"ez-toc-section\" id=\"Access_Solutions_to_the_NCERT_Exemplar_Class_12_Physics_Chapter_13\"><\/span>Access Solutions to the NCERT Exemplar Class 12 Physics Chapter 13<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><strong>Q. When a \u03b2-particle is emitted from a nucleus then its neutron-proton ratio:<\/strong><\/p>\n<p>(a) Increases<\/p>\n<p>(b) Decreases<\/p>\n<p>(c) Remains unchanged<\/p>\n<p>(d) May increase or decrease depending upon the nucleus<\/p>\n<p><strong>Answer:<\/strong> (b) Decreases<\/p>\n<p><strong>Q. In nuclear reactors, the control rods are made of:<\/strong><\/p>\n<p>(a) Cadmium<\/p>\n<p>(b) Graphite<\/p>\n<p>(c) Krypton<\/p>\n<p>(d) Plutonium<\/p>\n<p><strong>Answer:<\/strong> (a) Cadmium<\/p>\n<p><strong>Q. Light energy emitted by a star is due to:<\/strong><\/p>\n<p>(a) Breaking of nuclei<\/p>\n<p>(b) Joining of nuclei<\/p>\n<p>(c) Burning of nuclei<\/p>\n<p>(d) Reflection of solar light<\/p>\n<p><strong>Answer:<\/strong> (b) Joining of nuclei<\/p>\n<p><strong>Q. In nuclear reaction, there is conservation of:<\/strong><\/p>\n<p>(a) Mass only<\/p>\n<p>(b) Energy only<\/p>\n<p>(c) Momentum only<\/p>\n<p>(d) Mass, energy, and momentum<\/p>\n<p><strong>Answer:<\/strong> (d) Mass, energy, and momentum<\/p>\n<p style=\"text-align: center;\"><strong>Also Read: <a href=\"https:\/\/infinitylearn.com\/surge\/study-materials\/ncert-syllabus\/\">NCERT Syllabus<\/a><\/strong><\/p>\n<p><strong>Q. Tritium is an isotope of hydrogen whose nucleus contains 2 neutrons and 1 proton. Free neutrons decay into p + e + v. If one of the neutrons in Triton decays, it would transform into He-3 nucleus. This does not happen because:<\/strong><\/p>\n<p>(a) Triton energy is less than that of a He-3 nucleus<\/p>\n<p>(b) The electron created in the beta decay process cannot remain in the nucleus<\/p>\n<p>(c) Both the neutrons in triton have to decay simultaneously resulting in a nucleus with 3 protons, which is not a He-3 nucleus<\/p>\n<p>(d) Free neutrons decay due to external perturbations which is absent in a triton nucleus<\/p>\n<p><strong>Answer:<\/strong> (a) Triton energy is less than that of a He-3 nucleus<\/p>\n<p><strong>Q. Heavy stable nuclei have more neutrons than protons. This is because:<\/strong><\/p>\n<p>(a) Neutrons are heavier than protons<\/p>\n<p>(b) Electrostatic force between protons is repulsive<\/p>\n<p>(c) Neutrons decay into protons through beta decay<\/p>\n<p>(d) Nuclear forces between neutrons are weaker than that between protons<\/p>\n<p><strong>Answer:<\/strong> (b) Electrostatic force between protons is repulsive<\/p>\n<p><strong>Q. Fusion processes, like combining two deuterons to form a He nucleus, are impossible at ordinary temperatures and pressure. The reasons for this can be traced to the fact:<\/strong><\/p>\n<p>(a) Nuclear forces have short range<\/p>\n<p>(b) Nuclei are positively charged<\/p>\n<p>(c) The original nuclei must be completely ionized before fusion can take place<\/p>\n<p>(d) The original nuclei must first break up before combining with each other<\/p>\n<p><strong>Answer:<\/strong> (a) Nuclear forces have short range, (b) Nuclei are positively charged<\/p>\n<p><strong>Q. For thorium (A = 232 and Z = 90), at the end of some radioactive disintegrations, we obtain an isotope of lead with (A = 208, Z = 82). The number of emitted \u03b1 and \u03b2 particles are:<\/strong><\/p>\n<p>(a) \u03b1 = 4, \u03b2 = 6<\/p>\n<p>(b) \u03b1 = 5, \u03b2 = 5<\/p>\n<p>(c) \u03b1 = 6, \u03b2 = 4<\/p>\n<p>(d) \u03b1 = 6, \u03b2 = 6<\/p>\n<p><strong>Answer:<\/strong> (c) \u03b1 = 6, \u03b2 = 4<\/p>\n<p><strong>Q. If 10% of a radioactive material decays in 5 days, then the amount of the original material left after 20 days is nearly:<\/strong><\/p>\n<p>(a) 60%<\/p>\n<p>(b) 70%<\/p>\n<p>(c) 75%<\/p>\n<p>(d) 66%<\/p>\n<p><strong>Answer:<\/strong> (d) 66%<\/p>\n<p><strong>Q. Which of the following is the best nuclear fuel?<\/strong><\/p>\n<p>(a) Thorium-236<\/p>\n<p>(b) Plutonium-239<\/p>\n<p>(c) Neptunium-239<\/p>\n<p>(d) Uranium-236<\/p>\n<p><strong>Answer:<\/strong> (b) Plutonium-239<\/p>\n<p><strong>Q. Heavy water is used as a moderator in a nuclear reactor. The function of the moderator is to:<\/strong><\/p>\n<p>(a) Absorb neutrons and stop chain reaction<\/p>\n<p>(b) Cool the reactor<\/p>\n<p>(c) Slow down the neutrons to thermal energies<\/p>\n<p>(d) Control the energy released<\/p>\n<p><strong>Answer:<\/strong> (c) Slow down the neutrons to thermal energies<\/p>\n<p style=\"text-align: center;\"><strong>Read More:<a href=\"https:\/\/infinitylearn.com\/surge\/study-materials\/ncert-syllabus\/class-12\/\"> NCERT Syllabus Class 12<\/a><\/strong><\/p>\n<p><strong>Q. The volume of a nucleus is smaller than that of an atom by a factor of:<\/strong><\/p>\n<p>(a) 10<\/p>\n<p>(b) 10<sup>5<\/sup><\/p>\n<p>(c) 10<sup>15<\/sup><\/p>\n<p>(d) 10<sup>10<\/sup><\/p>\n<p><strong>Answer:<\/strong> (c) 10<sup>15<\/sup><\/p>\n<p><strong>Q. Fusion reactions take place at high temperature because:<\/strong><\/p>\n<p>(a) Kinetic energy is high enough to overcome repulsion between nuclei<\/p>\n<p>(b) Nuclei break up at high temperature<\/p>\n<p>(c) Atoms are ionized at high temperature<\/p>\n<p>(d) Molecules break up at high temperature<\/p>\n<p><strong>Answer:<\/strong> (a) Kinetic energy is high enough to overcome repulsion between nuclei<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Short_Answer_Types\"><\/span>Short Answer Types<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><strong>Q. Why do stable nuclei never have more protons than neutrons?<\/strong><\/p>\n<p>Ans. Stable nuclei have more neutrons than protons to counterbalance the repulsive electrostatic forces between protons through the strong nuclear force.<\/p>\n<p><strong>Q. Consider a radioactive nucleus A which decays to a stable nucleus C through the following sequence: A \u2192 B \u2192 C. Plot the graph showing the variation of the number of atoms of A and B versus time.<\/strong><\/p>\n<p>The number of atoms of A decreases exponentially over time, while B increases initially and then decreases as it decays into C, forming a peak on the graph.<\/p>\n<p><strong>Q. Are nucleons fundamental particles, or do they consist of smaller parts?<\/strong><\/p>\n<p>Ans. Nucleons are not fundamental particles; they consist of quarks held together by the strong nuclear force mediated by gluons.<\/p>\n<p><strong>Q. Why do heavy stable nuclei have more neutrons than protons?<\/strong><\/p>\n<p>Ans. Heavy stable nuclei have more neutrons than protons to mitigate the repulsive electrostatic forces between protons and to provide additional binding through the strong nuclear force.<\/p>\n<p><strong>Q. Explain why fusion processes like combining two deuterons to form a helium nucleus are impossible at ordinary temperatures and pressures.<\/strong><\/p>\n<p>Ans. Fusion requires extremely high temperatures and pressures to overcome the electrostatic repulsion between positively charged nuclei.<\/p>\n<p><strong>Q. Describe the role of a moderator in a nuclear reactor.<\/strong><\/p>\n<p>Ans. A moderator slows down the neutrons produced during fission to increase the probability of further fission reactions by maintaining the chain reaction.<\/p>\n<p><strong>Q. What is pair annihilation, and how is momentum conserved in this process?<\/strong><\/p>\n<p>Ans. Pair annihilation occurs when an electron and a positron destroy each other to produce gamma radiation. Momentum is conserved as the total momentum of the electron-positron pair is transferred to the photons produced.<\/p>\n<p><strong>Q. In radioactive decay, what is meant by the term &#8216;half-life&#8217;?<\/strong><\/p>\n<p>Ans. Half-life is the time required for half of the radioactive nuclei in a sample to decay.<\/p>\n<p><strong>Q. What are the products of alpha decay?<\/strong><\/p>\n<p>Ans. Alpha decay produces a new nucleus with a mass number reduced by 4 and an atomic number reduced by 2, along with an alpha particle( <sup>2<\/sup><sub>4<\/sub>He).<\/p>\n<p><strong>Q. Explain beta-minus decay.<\/strong><\/p>\n<p>Ans. Beta-minus decay occurs when a neutron in an unstable nucleus is converted into a proton, an electron (beta particle), and an antineutrino.<\/p>\n<p><strong>Q. What is the significance of binding energy per nucleon in nuclear stability?<\/strong><\/p>\n<p>Ans. The binding energy per nucleon indicates the stability of a nucleus; higher binding energy per nucleon implies a more stable nucleus.<\/p>\n<p><strong>Q. How does the mass defect of a nucleus relate to its binding energy?<\/strong><\/p>\n<p>Ans. The mass defect is the difference between the mass of a nucleus and the sum of its constituent nucleons. This mass defect, converted to energy, corresponds to the binding energy holding the nucleus together.<\/p>\n<p><strong>Q. What are isotopes and give an example?<\/strong><\/p>\n<p>Ans. Isotopes are atoms of the same element with different numbers of neutrons. Example: Carbon-12 and Carbon-14 are isotopes of Carbon.<\/p>\n<h4><span class=\"ez-toc-section\" id=\"More_Resources_for_Class_12\"><\/span>More Resources for Class 12<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ul>\n<li><a href=\"https:\/\/infinitylearn.com\/surge\/study-materials\/ncert-exemplar-solutions\/class-12\/chemistry\/\"><strong>NCERT Exemplar Solutions for Class 12 Chemistry<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/infinitylearn.com\/surge\/study-materials\/ncert-solutions\/class-12\/biology\/\"><strong>NCERT Exemplar Solutions for Class 12 Biology<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/infinitylearn.com\/surge\/study-materials\/ncert-exemplar-solutions\/class-12\/maths\/\"><strong>NCERT Exemplar Solutions for Class 12 Maths<\/strong><\/a><\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"Topics_Discussed_in_Class_12_Chapter_13_Nuclei\"><\/span>Topics Discussed in Class 12 Chapter 13 Nuclei<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<ol>\n<li>Introduction<\/li>\n<li>Atomic Masses and Composition of Nucleus<\/li>\n<li>Size of the Nucleus<\/li>\n<li>Mass-energy and Nuclear Binding Energy\n<ol>\n<li>Mass-energy<\/li>\n<li>Nuclear binding energy<\/li>\n<\/ol>\n<\/li>\n<li>Nuclear Force<\/li>\n<li>Radioactivity\n<ol>\n<li>Law of radioactive decay<\/li>\n<li>Alpha decay<\/li>\n<li>Beta-decay<\/li>\n<li>Gamma decay<\/li>\n<\/ol>\n<\/li>\n<li>Nuclear Energy\n<ol>\n<li>Fission<\/li>\n<li>Nuclear reactor<\/li>\n<li>Nuclear fusion \u2013 Energy generation in stars<\/li>\n<li>Controlled thermonuclear fusion<\/li>\n<\/ol>\n<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"<p>The NCERT Exemplar class 12 physics solutions for Chapter 13 Nuclei are meticulously prepared by the highly experienced faculty at [&hellip;]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_yoast_wpseo_focuskw":"NCERT Exemplar Class 12 Chemistry Chapter 13","_yoast_wpseo_title":"NCERT Exemplar Class 12 Chemistry Chapter 13 - 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