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Saturday, 31 October

JEE Main 2025 · PhysicsMultiple choiceAssertion–reasonEasyConceptual

JEE Main 7 April 2025, Shift 2, Physics Q44

Question 44 of 75 in this shift, Physics question 19 of 25, Section A.

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : The density of the copper (2964Cu)\left({}^{64}_{29}\mathrm{Cu}\right) nucleus is greater than that of the carbon (612C)\left({}^{12}_{6}\mathrm{C}\right) nucleus. Reason (R) : The nucleus of mass number AA has a radius proportional to A1/3A^{1/3}. In the light of the above statements, choose the most appropriate answer from the options given below :
  1. (1)Both (A) and (R) are correct and (R) is the correct explanation of (A)
  2. (2)Both (A) and (R) are correct but (R) is not the correct explanation of (A)
  3. (3)(A) is correct but (R) is not correct
  4. (4)(A) is not correct but (R) is correctOfficial answer

Official answer

Option 4

NTA final key.

Chapter
Nuclei
Topic
Nuclear Binding Energy
Idea tested
Nuclear Radius and Density

Same idea in other shifts

Asked 10× in all
  1. 8 Apr 2025, Shift 2 · Q44For a nucleus of mass number A and radius R, the mass density of nucleus can be represented asEasySingle correct
  2. 1 Feb 2024, Shift 1 · Q60The radius of a nucleus of mass number 64 is 4.8 fermi. Then the mass number of another nucleus having radius of 4 fermi is…EasyNumerical value
  3. 31 Jan 2024, Shift 2 · Q47The mass number of nucleus having radius equal to half of the radius of nucleus with mass number 192 is:EasySingle correct
  4. 31 Jan 2024, Shift 2 · Q60A nucleus has mass number A1A_1 and volume V1V_1. Another nucleus has mass number A2A_2 and Volume V2V_2. If relation between mass number…EasyNumerical value
  5. 11 Apr 2023, Shift 2 · Q55A nucleus disintegrates into two nuclear parts, in such a way that ratio of their nuclear sizes is 1:21/31 : 2^{1/3}. Their respective speed…MediumNumerical value
  6. 26 Jul 2022, Shift 2 · Q49Mass numbers of two nuclei are in the ratio of 4:3. Their nuclear densities will be in the ratio ofEasySingle correct
  7. 29 Jul 2022, Shift 2 · Q41Read the following statements: (A) Volume of the nucleus is directly proportional to the mass number. (B) Volume of the nucleus is…EasyOther
  8. 25 Jun 2022, Shift 2 · Q47Which of the following figure represents the variation of ln⁡(RR0)\ln\left(\frac{R}{R_0}\right) with lnA\mathrm{l}_n A (if RR = radius of a…EasyDiagram basedHas a figure

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.