{"id":28112,"date":"2019-10-31T16:23:54","date_gmt":"2019-10-31T10:53:54","guid":{"rendered":"http:\/\/mycbseguide.com\/blog\/?p=28112"},"modified":"2019-10-31T17:40:27","modified_gmt":"2019-10-31T12:10:27","slug":"cbse-class-12-atoms-chapter-12-physics-extra-questions","status":"publish","type":"post","link":"https:\/\/mycbseguide.com\/blog\/cbse-class-12-atoms-chapter-12-physics-extra-questions\/","title":{"rendered":"CBSE Class 12 Atoms Chapter 12 Physics Extra Questions"},"content":{"rendered":"<p><strong>CBSE Class 12 Atoms Chapter 12 Physics Extra Questions. <\/strong>We know Physics is tough subject within the consortium of science subjects physics is an important subject. But if you want to make career in these fields like IT Consultant, Lab Technician, Laser Engineer, Optical Engineer etc. You need to have strong fundamentals in physics to crack the exam.<strong>\u00a0<\/strong>myCBSEguide has just released Chapter Wise Question Answers for class 12 Physics. There chapter wise Extra Questions with complete solutions are available for download in\u00a0<strong><a href=\"https:\/\/mycbseguide.com\/\">myCBSEguide<\/a>\u00a0<\/strong>website and mobile app. These Questions with solution are prepared by our team of expert teachers who are teaching grade in CBSE schools for years. There are around 4-5 set of solved Physics Extra Questions from each and every chapter. The students will not miss any concept in these Chapter wise question that are specially designed to tackle Board Exam. We have taken care of every single concept given in\u00a0<strong><a href=\"https:\/\/mycbseguide.com\/course\/cbse-class-12-physics\/1251\/\">CBSE Class 12 Physics syllabus<\/a><\/strong>\u00a0and questions are framed as per the latest marking scheme and blue print issued by CBSE for class 12.<\/p>\n<div class=\"row\">\n<div class=\"col-md-12\">\n<div class=\"card\">\n<div class=\"row\">\n<div class=\"col-md-12\">\n<div class=\"card\">\n<p style=\"text-align: center;\"><strong>Class 12 Physics Extra Questions<\/strong><\/p>\n<p style=\"text-align: center;\"><strong><a class=\"button\" href=\"https:\/\/mycbseguide.com\/dashboard\/category\/1263\/type\/4\">Download as PDF<\/a><\/strong><\/p>\n<h2>Class 12 Physics Chapter 12 Practice Questions<\/h2>\n<p style=\"text-align: center;\"><strong>Class &#8211; 12 Physics (Atoms)<\/strong><\/p>\n<hr \/>\n<ol style=\"padding-left: 20px;\">\n<li class=\"question-list\" style=\"clear: both;\">\n<div class=\"question-container\">\n<div class=\"question-text\">\n<p>In the ground state of which model electrons are in stable equilibrium with zero net force?<\/p>\n<ol style=\"list-style-type: lower-alpha;\" start=\"1\">\n<li>No model<\/li>\n<li>Rutherford\u2019s model<\/li>\n<li>Thomson\u2019s model<\/li>\n<li>Bohr model<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<\/li>\n<li class=\"question-list\" style=\"clear: both;\">\n<div class=\"question-container\">\n<div class=\"question-text\">A triply ionized beryllium ion <span class=\"math-tex\">{tex}{\\rm{B}}{{\\rm{e}}^{{\\rm{3}} + }}{\/tex}<\/span>, (a beryllium atom with three electrons removed), behaves very much like a hydrogen atom except that the nuclear charge is four times as great. What is the ionization energy of <span class=\"math-tex\">{tex}{\\rm{B}}{{\\rm{e}}^{{\\rm{3}} + }}{\/tex}<\/span> ? How does this compare to the ionization energy of the hydrogen atom?<\/div>\n<ol style=\"list-style-type: lower-alpha;\" start=\"1\">\n<li class=\"question-text\"><span class=\"mcq_option_text\">248 eV, 16 times<\/span><\/li>\n<li class=\"question-text\"><span class=\"mcq_option_text\">218 eV, 16 times<\/span><\/li>\n<li class=\"question-text\"><span class=\"mcq_option_text\">268 eV, 16 times<\/span><\/li>\n<li class=\"question-text\"><span class=\"mcq_option_text\">218 eV, 16 times<\/span><\/li>\n<\/ol>\n<\/div>\n<\/li>\n<li class=\"question-list\" style=\"clear: both;\">\n<div class=\"question-container\">\n<div class=\"question-text\">\n<p>Which of these statements about Bohr model hypothesis is correct?<\/p>\n<ol style=\"list-style-type: lower-alpha;\" start=\"1\">\n<li>mass of electron is quantized<\/li>\n<li>velocity of electron is quantized<\/li>\n<li>angular momentum of electron is quantized<\/li>\n<li>radius of electron is quantized<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<\/li>\n<li class=\"question-list\" style=\"clear: both;\">\n<div class=\"question-container\">\n<div class=\"question-text\">\n<p>Which of these statements about Bohr model hypothesis is correct?<\/p>\n<ol style=\"list-style-type: lower-alpha;\" start=\"1\">\n<li>velocity of electron is quantized<\/li>\n<li>electron in a stable orbit emit quanta of light<\/li>\n<li>angular momentum is not quantized<\/li>\n<li>electron in a stable orbit does not radiate electromagnetic waves<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<\/li>\n<li class=\"question-list\" style=\"clear: both;\">\n<div class=\"question-container\">\n<div class=\"question-text\">\n<p>Which of the following transitions in a hydrogen emits the photon of the highest frequency?<\/p>\n<ol style=\"list-style-type: lower-alpha;\" start=\"1\">\n<li>n = 1 to n = 2<\/li>\n<li>n = 6 to n = 2<\/li>\n<li>n = 2 to n = 6<\/li>\n<li>n = 2 to n = 1<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<\/li>\n<li class=\"question-list\" style=\"clear: both;\">\n<div class=\"question-container\">\n<div class=\"question-text\">\n<p>Name the series of hydrogen spectrum which does not lie in the visible region.<\/p>\n<\/div>\n<\/div>\n<\/li>\n<li class=\"question-list\" style=\"clear: both;\">\n<div class=\"question-container\">\n<div class=\"question-text\">\n<p>Why is the classical (Rutherford) model for an atom of electron orbitting around the nucleus not able to explain the atomic structure?<\/p>\n<\/div>\n<\/div>\n<\/li>\n<li class=\"question-list\" style=\"clear: both;\">\n<div class=\"question-container\">\n<div class=\"question-text\">\n<p>The ground state energy of hydrogen atom is -13.6 eV. What are the kinetic and potential energies of the electron in this state?<\/p>\n<\/div>\n<\/div>\n<\/li>\n<li class=\"question-list\" style=\"clear: both;\">\n<div class=\"question-container\">\n<div class=\"question-text\">\n<p>What is the impact parameter for scattering of <span class=\"math-tex\">{tex}\\alpha {\/tex}<\/span>-particle by 180\u00b0?<\/p>\n<\/div>\n<\/div>\n<\/li>\n<li class=\"question-list\" style=\"clear: both;\">\n<div class=\"question-container\">\n<div class=\"question-text\">\n<p>An <span class=\"math-tex\">{tex}\\alpha{\/tex}<\/span>-particle moving with initial kinetic energy <i>K <\/i>towards a nucleus of atomic number <i>Z <\/i>approaches a distance <i>d <\/i>at which it reverses its direction. Obtain the expression for the distance of closest approach <i>d <\/i>in terms of the kinetic energy of <span class=\"math-tex\">{tex}\\alpha{\/tex}<\/span>-particle K<i>. <\/i><\/p>\n<\/div>\n<\/div>\n<\/li>\n<li class=\"question-list\" style=\"clear: both;\">\n<div class=\"question-container\">\n<div class=\"question-text\">\n<p>Find the ratio between the wavelengths of the &#8216;most energetic&#8217; spectral lines in the Balmer and Paschen series of the hydrogen spectrum.<\/p>\n<\/div>\n<\/div>\n<\/li>\n<li class=\"question-list\" style=\"clear: both;\">\n<div class=\"question-container\">\n<div class=\"question-text\">\n<p>The ground state energy of hydrogen atoms is -13.6 eV.<\/p>\n<ol style=\"list-style-type: lower-roman;\" start=\"1\">\n<li>Which are the potential and kinetic energy of an electron in the third excited state?<\/li>\n<li>If the electron jumps to the ground state from the third excited state. Calculate the frequency of photon emitted.<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<\/li>\n<li class=\"question-list\" style=\"clear: both;\">\n<div class=\"question-container\">\n<div class=\"question-text\">\n<p>Using the relevant Bohr&#8217;s postulates, derive the expressions for the (i) speed of the electron in the nth orbit, (ii) radius of the nth orbit of the electron in hydrogen atom.<\/p>\n<\/div>\n<\/div>\n<\/li>\n<li class=\"question-list\" style=\"clear: both;\">\n<div class=\"question-container\">\n<div class=\"question-text\">\n<p>Which state of the triply ionized Be<sup>+++<\/sup> has the same orbital radius as that of the ground state of hydrogen? Compare the energies of two states.<\/p>\n<\/div>\n<\/div>\n<\/li>\n<li class=\"question-list\" style=\"clear: both;\">\n<div class=\"question-container\">\n<div class=\"question-text\">\n<p>(a) The energy levels of an atom are as shown below. Which of them will result in the transition of a photon of wavelength 275 nm?<br \/>\n(b) Which transition corresponds to emission of radiation of maximum wavelength?<\/p>\n<\/div>\n<\/div>\n<\/li>\n<\/ol>\n<p style=\"page-break-before: always; text-align: center;\"><strong>Class &#8211; 12 Physics (Atoms)<\/strong><br \/>\n<strong>Answers<\/strong><\/p>\n<hr \/>\n<ol style=\"padding-left: 20px;\">\n<li class=\"question-list\" style=\"clear: both;\">\n<ol style=\"margin-top: 5px; padding-left: 15px; list-style-type: lower-alpha;\" start=\"3\" type=\"a\">\n<li>Thomson\u2019s model<br \/>\n<strong>Explanation:\u00a0<\/strong>In the atomic model proposed by J J Thomson, there are positive charges inside an atom and they neutralise the negative charge of the electron. Thus the electrons in this model are in stable equilibrium in the ground state.<\/li>\n<\/ol>\n<ol style=\"margin-top: 5px; padding-left: 15px; list-style-type: lower-alpha;\" start=\"4\" type=\"a\">\n<li>218 eV, 16 times<br \/>\n<strong>Explanation:\u00a0<\/strong>Ionization energy is energy required to remove electron from atom.<br \/>\nEnergy = E<sub>n <\/sub>&#8211; E<sub>1<\/sub> = &#8211; E<sub>1<\/sub><br \/>\nn = infinity, E<sub>n<\/sub> = 0<\/li>\n<\/ol>\n<ol style=\"margin-top: 5px; padding-left: 15px; list-style-type: lower-alpha;\" start=\"3\" type=\"a\">\n<li>angular momentum of electron is quantized<br \/>\n<strong>Explanation:\u00a0<\/strong>By Bohr&#8217;s second postulate, the electron revolves around the nucleus only in those orbits for which the angular momentum is an integral mutiple of <span class=\"math-tex\">{tex}{h \\over 2 \\pi}{\/tex}<\/span>, where h is the Plancks constant. So angular momentum (L) of the orbiting electron is quantized.<\/li>\n<\/ol>\n<ol style=\"margin-top: 5px; padding-left: 15px; list-style-type: lower-alpha;\" start=\"4\" type=\"a\">\n<li>electron in a stable orbit does not radiate electromagnetic waves<br \/>\n<strong>Explanation:\u00a0<\/strong>Bohr&#8217;s first postulate:<br \/>\nAn electron in an atom could revolve in certain stable orbits without the emission of radiant energy.<br \/>\nAccording to this postulate, each atom has certain definite stable state in which it can exist. They do not emit energy when they are in these states. These are called the stationary states of the atom.<\/li>\n<\/ol>\n<ol style=\"margin-top: 5px; padding-left: 15px; list-style-type: lower-alpha;\" start=\"2\" type=\"a\">\n<li>n = 6 to n = 2<br \/>\n<strong>Explanation: <\/strong>According to Bohr&#8217;s third postulate: When an atom makes a transition from the higher energy state n<sub>i<\/sub> to the lower energy state n<sub>f <\/sub>(n<sub>f<\/sub> &lt; n<sub>i<\/sub>), the difference of energy is emitted as a photon of frequency<\/li>\n<\/ol>\n<\/li>\n<li class=\"question-list\" style=\"clear: both;\">The series is named after its discoverer, Theodore Lyman, who discovered the spectral lines from 1906\u20131914. All the wavelengths in the Lyman series are in the ultraviolet band.<\/li>\n<li class=\"question-list\" style=\"clear: both;\">Rutherford&#8217;s model was unable to explain the stability of an atom. According to Rutherford&#8217;s postulate, electrons revolve at a very high speed around a nucleus of an atom in a fixed orbit. Therefore, Rutherford&#8217;s atomic model was not following Maxwell&#8217;s theory and it was unable to explain an atom&#8217;s stability.<\/li>\n<li class=\"question-list\" style=\"clear: both;\">The ground state energy of hydrogen atom is -13.6 eV.<br \/>\nGiven,total ground state energy = -13.6eV<br \/>\nwe know that,<br \/>\nKinetic energy = &#8211; Total Energy = &#8211; (-13.6 eV)= 13.6eV<br \/>\nand<br \/>\nPotential energy= 2 (TE) = 2 <span class=\"math-tex\">{tex} \\times {\/tex}<\/span> (-13.6 )= &#8211; 27.2 eV<\/li>\n<li class=\"question-list\" style=\"clear: both;\">Zero.<br \/>\nSince, Impact parameter, <span class=\"math-tex\">{tex}b = \\frac{{Z{e^2}\\cot \\frac{\\theta }{2}}}{{4\\pi {\\varepsilon _0}\\left( {\\frac{1}{2}m{v^2}} \\right)}}{\/tex}<\/span><br \/>\nWe will have <span class=\"math-tex\">{tex}cot 90^0 = 0{\/tex}<\/span><br \/>\nSo impact will be zero.<\/li>\n<li class=\"question-list\" style=\"clear: both;\">When alpha particle approaches Nucleus, Kinetic energy of alpha particle will be converted into potential energy of the system.Kinetic energy of <span class=\"math-tex\">{tex}\\alpha{\/tex}<\/span>-particle is given as,<br \/>\n<span class=\"math-tex\">{tex}K = \\frac { 1 } { 4 \\pi \\varepsilon _ { 0 } } \\frac { 2 e . Z e } { d ^ { 2 } }{\/tex}<\/span><br \/>\nwhere d is the distance of closest approach.<br \/>\n<span class=\"math-tex\">{tex}d ^ { 2 } = \\frac { 2 Z e ^ { 2 } } { 4 \\pi \\varepsilon _ { 0 } K } \\Rightarrow d = \\sqrt { \\frac { 2 Z e ^ { 2 } } { 4 \\pi \\varepsilon _ { 0 } K } }{\/tex}<\/span><br \/>\nThis is the required expression for the distance of closest approach d in terms of kinetic energy K.<\/li>\n<li class=\"question-list\" style=\"clear: both;\">As per the Bohr&#8217;s Model, the wavelengths are given by<br \/>\n<span class=\"math-tex\">{tex}\\frac { 1 } { \\lambda } = R \\left( \\frac { 1 } { n_1 ^ { 2 } } &#8211; \\frac { 1 } { n_2 ^ { 2 } } \\right){\/tex}<\/span><br \/>\nFor Balmer series, <span class=\"math-tex\">{tex}\\frac { 1 } { \\lambda _ { B } } = R \\left( \\frac { 1 } { 2 ^ { 2 } } &#8211; \\frac { 1 } { n ^ { 2 } } \\right){\/tex}<\/span><br \/>\nFor highest energy n <span class=\"math-tex\">{tex}\\to \\infty{\/tex}<\/span><br \/>\n<span class=\"math-tex\">{tex}\\Rightarrow \\quad \\frac { 1 } { \\lambda _ { B } } = \\frac { R } { 2 ^ { 2 } } = \\frac { R } { 4 } \\Rightarrow \\lambda _ { B } = \\frac { 4 } { R }{\/tex}<\/span><br \/>\nFor Paschen series,<span class=\"math-tex\">{tex}\\frac { 1 } { \\lambda _ { p } } = R \\left( \\frac { 1 } { 3 ^ { 2 } } &#8211; \\frac { 1 } { n ^ { 2 } } \\right){\/tex}<\/span><br \/>\nFor highest energy n <span class=\"math-tex\">{tex}\\to \\infty{\/tex}<\/span><br \/>\n<span class=\"math-tex\">{tex}\\Rightarrow \\quad \\lambda _ { p } = \\frac { 9 } { R } \\Rightarrow \\lambda _ { B } : \\lambda _ { P } = \\frac { 4 } { R } : \\frac { 9 } { R } \\Rightarrow 4 : 9{\/tex}<\/span><\/p>\n<ol style=\"list-style-type: lower-roman;\" start=\"1\">\n<li>In hydrogen atom in the ground state<br \/>\n<span class=\"math-tex\">{tex}E = &#8211; (K.E.) = \\frac{1}{2}(P.E.){\/tex}<\/span><br \/>\n<span class=\"math-tex\">{tex}\\therefore {\/tex}<\/span> Potential energy of electron in third excited state<br \/>\n<span class=\"math-tex\">{tex} = \\frac{{2(E)}}{{{{(4)}^2}}} = &#8211; \\frac{{2 \\times 13.6}}{{16}}eV{\/tex}<\/span><br \/>\n= -1.7 eV<br \/>\n<span class=\"math-tex\">{tex} = &#8211; \\frac{1}{2}(1.7) = 0.85eV{\/tex}<\/span><\/li>\n<li><span class=\"math-tex\">{tex}\\nu = \\frac{{\\Delta E}}{h} = \\left[ {\\frac{{ &#8211; 13.6}}{{{{(4)}^2}}} + \\frac{{13.6}}{{{{(1)}^2}}}} \\right]\\frac{{1.6 \\times {{10}^{ &#8211; 19}}}}{{6.6 \\times {{10}^{ &#8211; 34}}}}{\/tex}<\/span><br \/>\n<span class=\"math-tex\">{tex} = \\frac{{11.9 \\times 1.6 \\times {{10}^{ &#8211; 19}}}}{{6.6 \\times {{10}^{ &#8211; 34}}}}Hz{\/tex}<\/span><br \/>\n<span class=\"math-tex\">{tex} \\approx 2.9 \\times {10^{15}}Hz{\/tex}<\/span><\/li>\n<\/ol>\n<ol style=\"list-style-type: lower-roman;\" start=\"1\">\n<li>Speed of the electron in nth orbit<br \/>\nCentnpetal force of revolution is provided by electrostatic force of attraction.<br \/>\nmv<sup>2<\/sup>\/r = ke<sup>2<\/sup>\/r<sup>2<\/sup><br \/>\nr = ke<sup>2<\/sup>\/mv<sup>2<\/sup>&#8230;&#8230;&#8230;(i)<br \/>\nAlso, from Bohr&#8217;s postulates<br \/>\n<span class=\"math-tex\">{tex}m v r = \\frac { n h } { 2 \\pi } \\Rightarrow r = \\frac { n h } { 2 \\pi m v }{\/tex}<\/span>&#8230;&#8230;&#8230;(ii)<br \/>\nOn comparing Eqs. (i) and (ii), we get<br \/>\n<span class=\"math-tex\">{tex}\\frac { k e ^ { 2 } } { m v ^ { 2 } } = \\frac { n h } { 2 \\pi m v } \\Rightarrow v = \\frac { 2 \\pi k e ^ { 2 } } { n h }{\/tex}<\/span>&#8230;&#8230;&#8230;..(iii)<br \/>\nor <span class=\"math-tex\">{tex}v = \\left( \\frac { 2 \\pi K e ^ { 2 } } { c h } \\right) \\frac { c } { n } \\left[ \\because k = \\frac { 1 } { 4 \\pi \\varepsilon _ { 0 } } \\right] {\/tex}<\/span><br \/>\nwhere, c =velocity of light<br \/>\nor <span class=\"math-tex\">{tex}v = \\alpha \\frac { c } { n }{\/tex}<\/span> &#8230;&#8230;&#8230;.(iv)<br \/>\nwhere, <span class=\"math-tex\">{tex}\\alpha = 2 \\pi k e ^ { 2 } \/ c h{\/tex}<\/span> and known as fine structure constant.<br \/>\nAlso, <span class=\"math-tex\">{tex}\\alpha = \\frac { 1 } { 137 }{\/tex}<\/span><br \/>\n<span class=\"math-tex\">{tex}\\Rightarrow \\quad v = \\frac { 1 } { 137 } \\frac { c } { n }{\/tex}<\/span>&#8230;&#8230;&#8230;&#8230;(v)<br \/>\nFor, n = 1, <span class=\"math-tex\">{tex}v = \\frac { 1 } { 137 } \\times c{\/tex}<\/span><br \/>\nIn K-shell of hydrogen atom, electron revolves with <span class=\"math-tex\">{tex}\\frac{1}{137}{\/tex}<\/span> times of speed of light.<\/li>\n<li>Expression for Bohr&#8217;s radius in hydrogen atom<br \/>\n<span class=\"math-tex\">{tex}r _ { n } = \\frac { n ^ { 2 } h ^ { 2 } } { 4 \\pi ^ { 2 } m k Z e ^ { 2 } } \\Rightarrow r _ { 1 } = \\frac { n ^ { 2 } h ^ { 2 } } { 4 \\pi ^ { 2 } m k e ^ { 2 } }{\/tex}<\/span><br \/>\nwhere, n = principal quantum number,<br \/>\nm = mass of electron<br \/>\n<span class=\"math-tex\">{tex}k=\\frac{1}{{4\\pi}\\varepsilon _ { 0 }}{\/tex}<\/span><br \/>\nZ =atomic number of atom = 1 and<br \/>\nh =Planck&#8217;s constant<\/li>\n<\/ol>\n<\/li>\n<li class=\"question-list\" style=\"clear: both;\">Radius of n<sup>th<\/sup> orbit is given by<br \/>\n<span class=\"math-tex\">{tex}r = \\frac{{{n^2}{h^2}}}{{4{\\pi ^2}mKZ{e^2}}}{\/tex}<\/span> i.e. <span class=\"math-tex\">{tex}r\\propto\\frac{{{n^2}}}{Z}{\/tex}<\/span><br \/>\nFor hydrogen, Z = 1, n =1 in ground state<br \/>\n<span class=\"math-tex\">{tex}\\therefore \\frac{{{n^2}}}{Z} = \\frac{{{1^2}}}{1} = 1{\/tex}<\/span><br \/>\nFor Beryleum, Z = 4, as orbital radius is same, <span class=\"math-tex\">{tex}\\frac{{{n^2}}}{Z} = 1{\/tex}<\/span><br \/>\n<span class=\"math-tex\">{tex}\\therefore {n^2} = 1 \\times Z = 1 \\times 4 = 4{\/tex}<\/span><br \/>\n<span class=\"math-tex\">{tex}n = \\sqrt 4 = 2{\/tex}<\/span><br \/>\nHence n = 2 level of Be has same radius as n =1 level of hydrogen.<br \/>\nNow, energy of electron in nth orbit is <span class=\"math-tex\">{tex}E = &#8211; \\frac{{2{\\pi ^2}m{K^2}{Z^2}{e^4}}}{{{n^2}{h^2}}}{\/tex}<\/span><br \/>\n<span class=\"math-tex\">{tex}\\therefore E\\propto\\frac{{{Z^2}}}{{{n^2}}}{\/tex}<\/span><br \/>\n<span class=\"math-tex\">{tex}\\frac{{{E_{(Be)}}}}{{{E_{(H)}}}} = \\frac{{{{\\left[ {\\frac{{{Z^2}}}{{{n^2}}}} \\right]}_{Be}}}}{{{{\\left[ {\\frac{{{Z^2}}}{{{n^2}}}} \\right]}_H}}} = \\frac{{\\frac{{16}}{4}}}{{\\frac{1}{1}}} = 4{\/tex}<\/span><\/li>\n<li class=\"question-list\" style=\"clear: both;\">(a) For element A<br \/>\nGround state energy, E<sub>1<\/sub> = -2eV<br \/>\nExcited state energy, E<sub>2<\/sub> = 0eV<br \/>\nEnergy of photon emitted, E = E<sub>2<\/sub> &#8211; E<sub>1<\/sub><br \/>\n= 0 &#8211; (-2) = 2eV<br \/>\nWavelength of photon emitted,<br \/>\n<span class=\"math-tex\">{tex}\\lambda = \\frac{{hc}}{E}{\/tex}<\/span><br \/>\n<span class=\"math-tex\">{tex} = \\frac{{6.63 \\times {{10}^{ &#8211; 34}} \\times 3 \\times {{10}^8}}}{{2 \\times 1.6 \\times {{10}^{ &#8211; 19}}}} = \\frac{{19.878 \\times {{10}^{ &#8211; 7}}}}{{3.2}}{\/tex}<\/span><br \/>\n<span class=\"math-tex\">{tex} = 6.211 \\times {10^{ &#8211; 7}}m{\/tex}<\/span>= 621.1 nm<br \/>\nFor element B<br \/>\nE<sub>1<\/sub> = -4.5 eV, E<sub>2<\/sub> = 0eV<br \/>\nE = 0 &#8211; (-4.5) = 4.5eV<br \/>\n<span class=\"math-tex\">{tex}\\therefore \\lambda = \\frac{{6.63 \\times {{10}^{ &#8211; 34}} \\times 3 \\times {{10}^8}}}{{4.5 \\times 1.6 \\times {{10}^{ &#8211; 19}}}} = \\frac{{19.878 \\times {{10}^{ &#8211; 7}}}}{{7.2}}{\/tex}<\/span><br \/>\n<span class=\"math-tex\">{tex} = 2.76 \\times {10^{ &#8211; 7}}{\/tex}<\/span>= 276 nm<br \/>\nFor element C<br \/>\nE<sub>1<\/sub> = -4.5eV, E<sub>2<\/sub> = -2eV<br \/>\nE = -2 &#8211; (4.5) = 2.5 eV<br \/>\n<span class=\"math-tex\">{tex}\\therefore \\lambda = \\frac{{6.63 \\times {{10}^{ &#8211; 34}} \\times 3 \\times {{10}^8}}}{{2.5 \\times 1.6 \\times {{10}^{ &#8211; 19}}}} = \\frac{{19.878 \\times {{10}^{ &#8211; 7}}}}{4}{\/tex}<\/span><br \/>\n<span class=\"math-tex\">{tex} = 4.969 \\times {10^{ &#8211; 7}}m = 496.9nm{\/tex}<\/span><br \/>\nFor element D<br \/>\nE<sub>1<\/sub> = -10eV, E<sub>2<\/sub> = -2eV<br \/>\nE = -2 &#8211; (-10) = 8eV<br \/>\n<span class=\"math-tex\">{tex}\\therefore \\lambda = \\frac{{6.63 \\times {{10}^{ &#8211; 34}} \\times 3 \\times {{10}^8}}}{{8 \\times 1.6 \\times {{10}^{ &#8211; 19}}}} = \\frac{{19.878 \\times {{10}^{ &#8211; 7}}}}{{12.8}}{\/tex}<\/span><br \/>\n<span class=\"math-tex\">{tex} = 1.552 \\times {10^{ &#8211; 7}}m = 155.2nm{\/tex}<\/span><br \/>\n(b) Element A has radiation of maximum wavelength 621 nm.<\/li>\n<\/ol>\n<div class=\"row\">\n<div class=\"col-md-12\">\n<div class=\"card\">\n<div class=\"row\">\n<div class=\"col-md-12\">\n<div class=\"card\">\n<h2>Chapter Wise Extra Questions of Class 12 Physics Part I &amp; Part II<\/h2>\n<ol>\n<li><a href=\"https:\/\/mycbseguide.com\/blog\/cbse-important-questions-for-class-12-physics-chapter-1\/\">Electric Charges and Fields<\/a><\/li>\n<li><a href=\"https:\/\/mycbseguide.com\/blog\/cbse-class-12-physics-chapter-2-extra-questions\/\">Electrostatic Potential and Capacitance<\/a><\/li>\n<li><a href=\"https:\/\/mycbseguide.com\/blog\/current-electricity-chapter-1-extra-questions-for-class-12-physics\/\">Current Electricity<\/a><\/li>\n<li><a href=\"https:\/\/mycbseguide.com\/blog\/cbse-class-12-physics-chapter-4-important-questions\/\">Moving Charges and Magnetism<\/a><\/li>\n<li><a href=\"https:\/\/mycbseguide.com\/blog\/cbse-class-12-physics-magnetism-and-matter-important-questions\/\">Magnetism and Matter<\/a><\/li>\n<li><a href=\"https:\/\/mycbseguide.com\/blog\/electromagnetic-induction-class-12-physics-important-questions\/\">Electromagnetic Induction<\/a><\/li>\n<li><a href=\"https:\/\/mycbseguide.com\/blog\/alternating-current-class-12-physics-extra-questions\/\">Alternating Current<\/a><\/li>\n<li><a href=\"https:\/\/mycbseguide.com\/blog\/cbse-class-12-physics-electromagnetic-waves-important-questions\/\">Electromagnetic Waves<\/a><\/li>\n<li><a href=\"https:\/\/mycbseguide.com\/blog\/cbse-class-12-physics-chapter-9-extra-questions\/\">Ray Optics and Optical<\/a><\/li>\n<li><a href=\"https:\/\/mycbseguide.com\/blog\/important-questions-for-class-12-physics-chapter-10-wave-optics\/\">Wave Optics<\/a><\/li>\n<li><a href=\"https:\/\/mycbseguide.com\/blog\/cbse-class-12-chapter-11-physics-important-questions\/\">Dual Nature of Radiation and Matter<\/a><\/li>\n<li><a href=\"https:\/\/mycbseguide.com\/blog\/cbse-class-12-atoms-chapter-12-physics-extra-questions\/\">Atoms<\/a><\/li>\n<li><a href=\"https:\/\/mycbseguide.com\/blog\/cbse-class-12-physics-chapter-13-nuclei-important-questions\/\">Nuclei<\/a><\/li>\n<li><a href=\"https:\/\/mycbseguide.com\/blog\/extra-questions-for-class-12-physics-electronic-devices\/\">Electronic Devices<\/a><\/li>\n<\/ol>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>CBSE Class 12 Atoms Chapter 12 Physics Extra Questions. We know Physics is tough subject within the consortium of science subjects physics is an important subject. But if you want to make career in these fields like IT Consultant, Lab Technician, Laser Engineer, Optical Engineer etc. You need to have strong fundamentals in physics to &#8230; <a title=\"CBSE Class 12 Atoms Chapter 12 Physics Extra Questions\" class=\"read-more\" href=\"https:\/\/mycbseguide.com\/blog\/cbse-class-12-atoms-chapter-12-physics-extra-questions\/\" aria-label=\"More on CBSE Class 12 Atoms Chapter 12 Physics Extra Questions\">Read more<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1346,1433],"tags":[1869,1871,1839,1838,1833,1832],"class_list":["post-28112","post","type-post","status-publish","format-standard","hentry","category-cbse","category-physics-cbse-class-12","tag-cbse-class-12-physics","tag-chapter-wise-important-questions","tag-extra-questions","tag-important-questions","tag-latest-exam-questions","tag-practice-questions"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.0 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>CBSE Class 12 Atoms Chapter 12 Physics Extra Questions<\/title>\n<meta name=\"description\" content=\"CBSE Class 12 Atoms Chapter 12 Physics Extra Questions But if you want to make career in these fields like IT Consultant, Lab Technician, etc\" \/>\n<meta name=\"robots\" content=\"index, follow, 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