CBSE Class 12 Physics Competency-Based Questions With Answer Key 2024-25: Chapter 5 Atoms and Nuclei FREE PDF Download

CBSE 2024-25 Competency-Based Questions With Answers: The Central Baord of Secondary Education has officially released the practice question paper for the academic year 2024-25, for the classes 10th  and 12th. Competency-focused questions can be helpful for students to secure good marks while referring and practicing them. It will help students to get familiar with the style and format of questions which are expected to appear in the final examinations.

The questions are designied chapter-wise for all the major subject of class 12th. In this article you will find specifically for Class 12 Physics Chapter 5  Atoms and Nuclei, the CBSE Board has given the practice question paper for students to understand and up skill there preparation for 2025 examination. At the end of this article free PDF has been attached for the students to access and download. 

CBSE Class 12 Physics Chapter 5 Competency-Based Questions

Question 1: If an electron in a hydrogen atom undergoes transition from 1st to 3rd energy 

level, by what factor does the time period of revolution undergo a change? 

1. remains the same 
2. becomes 3 times the initial value 
3. becomes 9 times the initial value 
4. becomes 27 times the initial value 

Question 2: Hydrogen atom at its ground  state is excited  by  incident photons  of energy 

12.75 eV. What is the expected count of the distinct spectral lines emitted by 

this hydrogen atom? 

1. 3 
2. 5 
3. 6 
4. 8

Question 3:  An electron in the Bohr model atom is in the nth orbit of radius r and has kinetic energy  KE.  Which  of  the  following  statements  does  not  comply  with  the postulate of Bohr’s model of atom? 

1. Radius of the orbit in terms of de Broglie wavelength is given as nλ/2π 
2. In  going  from  lower  to  higher  orbit,  both  PE  and  TE  increases  but  KE decreases. 
3. If KE = 3.4 eV, the corresponding potential energy PE is 6.8 eV and Total energy TE is 10.2 eV 
4. If  the  ionization  potential  of  the  given  Bohr  model  atom  is  13.6  V,  the energy required to remove the electron from its second orbit is 3.4 eV. 

Question 4: Choose the only correct statement. 

1. In a stable nucleus, the number of neutrons ≥ number of protons. 
2. Nuclei with atomic number greater than 82 show a tendency to fuse. 
3. A stable nucleus in general has even number of protons and odd number of neutrons. 
4. The proton‐proton nuclear force > proton‐neutron nuclear force > neutron‐ neutron nuclear force. 

Question 5:  Binding energy values of a few nuclei are given in the table below.

Lithium‐7	Iron ‐56	Lead ‐ 206	Deuterium ‐2
40.1 MeV	492.2 MeV	1622 MeV	2.2 MeV

The least and the most stable nuclei respectively are: 

1. Lead and Lithium 
2. Lithium and Deuterium 
3. Deuterium and Iron 
4. Iron and Lead 

Question 6: Study the following statements carefully and identify the correct statement/s. 

I. The nuclear pairs, ₇N¹⁴ and ₆C¹³ & ₁₅P³⁰ and ₁₄Si³⁰, both constitute isobars. 

II. ₇N¹⁴ can absorb a neutron and transform into ^₃Li⁷ after emitting 2 alpha particles and a proton. 

III. If 5.6 MeV is required to remove 1 neutron from  _³Li⁷ and transform it to  _³Li⁶, then it is also the BE per nucleon of _³Li⁶

IV. If M is the mass of the nucleus ₁₃Al²⁷, and m_p & m_n are the masses of protons and neutrons respectively, the binding energy of the nucleus is [|M ‐ 13m_p ‐ 14m_n |c² ] 

1. Only statement III 
2. Only statements I and III 
3. Only statements II and IV 
4. Only statements III and IV

Question 7:  Which of the following statements are INCORRECT for atomic nuclei? 

1. As mass number A increases, the density of the nucleus does not change. 
2. Heavier nuclei tend to have larger Z/N ratio as Coulomb forces have longer range compared to nuclear forces. 
3. For  nuclei  with  A  >  100,  the  binding  energy  per  nucleon  of  the nucleus decreases on an average as A increases. 
4. Two  Lithium  nuclei  do  not  combine  to  form  carbon  nuclei  at  room temperature because Coulomb repulsions do not allow them to come very close. 

Question 8: Particles  like  electron,  protons  and  alpha  particles  can  be  used  to  ionize  hydrogen atom. If  the ionization energy of hydrogen atom is Ei and all these  striking particles carry same kinetic energies,  then determine which of  these  particles will be most effective in ionizing the hydrogen atom? Assume that the collisions are perfectly inelastic and it’s the excess KE that is  used for ionisation.  

Question 9:  An ultraviolet radiation falls on a H atom. 

(a) If the H atom is in the ground state when the incident photon of wavelength 80 nm falls on it, will the H atom get excited to the higher energy levels? OR will the H atom get ionized? Justify your answer. 

(b) Post your answer of part (a), Determine EITHER  the quantum number of  the energy level  to which  the H atom gets excited OR determine the KE of the electron emitted out of the H atom. Use value of hc = 1240 eV‐nm 

Question 10: (a) Show that it takes more energy, in general, to remove a neutron from a  nucleus than a proton. Use the example of Z A X and the below data for the purpose‐of‐explanation.  

Mass‐of _Z ^A X=63.546u  

Mass_proton =1.0073u  

Mass_neutron =1.0087u  

Massof _Z ^A‐1X=62.5493u  

Mass of _Z‐1 ^A‐1Y = 62.5467 u (b) Give reason: Why does it take more energy to  separate a neutron from the nucleus than a proton? 

To access all the practice question of Physics Chapter 5 Electromagnetic Induction and Alternating Current, the complete FREE PDFs are attached here. Click on the 'Download PDF' to get the PDF.

CBSE Class 12 Physics Competency-Based Questions With Answer Key 2024-25

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Tips To Prepare For Board Exam 

Preparing for board exams can be challenging, but with right strategies and techniques you can approach your studies in right direction. Here are some tips which will help you to prepare for board exams: 

• Make a Study Plan: Making study plan befor exam will beneficial for students. 
• Understand the Syllabus: Make sure you are familiarise your exam syllabus and ensure you cover all topics. 
• Use Study Materials: Use additional reference books and guides for more in-depth understanding if necessary.
• Practice Last Year Papers: Practice last year board exam sample papers to get a feel for the types of questions asked and the exam format. 
• Focus on conceptual understanding: Ensure you understand the concepts thoroughly.
• Regular Revision: Regularly revise what you've studied and make concise notes for quick revision of key points.

By following these tips, you can improve your preparation for board exams and increase your chances of achieving your desired results.