JEE Main 2021 · PhysicsMultiple choiceSingle correctMediumConceptual

JEE Main 18 March 2021, Shift 2, Physics Q20

Question 20 of 90 in this shift, Physics question 20 of 30, Section A.

The decay of a proton to neutron is :

(1)not possible as proton mass is less than the neutron mass
(2)possible only inside the nucleusOfficial answer
(3)always possible as it is associated only with $\beta^+$ decay
(4)not possible but neutron to proton conversion is possible

Official answer

Option 2

NTA final key.

Chapter: Nuclei
Topic: Radioactive Decay
Idea tested: Beta Decay Mechanisms

Same topic in other shifts

All Radioactive Decay questions

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4 Apr 2025, Shift 2 · Q42A radioactive material P first decays into Q and then Q decays to non-radioactive material R. Which of the following figure represents…MediumDiagram basedHas a figure
8 Apr 2023, Shift 2 · Q44A radio active material is reduced to 1/8 of its original amount in 3 days. If $8\times10^{-3}$ kg of the material is left after 5 days…MediumSingle correct
10 Apr 2023, Shift 1 · Q56The decay constant for a radioactive nuclide is $1.5\times10^{-5}\,s^{-1}$ . Atomic weight of the substance is 60 g mole $^{-1}$ , (…EasyNumerical value
10 Apr 2023, Shift 2 · Q44The half life of a radioactive substance is T. The time taken, for disintegrating $\frac{7}{8}$ th part of its original mass will be:EasySingle correct
11 Apr 2023, Shift 1 · Q33Two radioactive elements A and B initially have same number of atoms. The half life of A is same as the average life of B. If $\lambda_A$ …EasySingle correct

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.