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Nuclei

JEE Main 2025 (Online) 4th April Evening ShiftMCQEasy📈 Topic in 3% papers+4−1
Ques. 1JEE Main 2025, 4 April (Evening Shift)

A radioactive material P first decays into Q and then Q decays to non-radioactive material R. Which of the following figure represents time dependent mass of P, Q and R ?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]

Answer

(2) [figure]

Solution

P (parent) decays exponentially: mP=m0e- 1 t, so its mass falls continuously from its maximum value

Q is formed from P and also decays: its mass starts from zero, rises while the rate of formation exceeds the rate of decay, reaches a maximum and then decreases towards zero

R is stable: its mass starts from zero and increases continuously, finally approaching the initial mass m0 (saturation)

Only figure (2) shows P decreasing, Q rising to a maximum and then falling, and R rising to saturation

Answer: (2)

Keep practising — Nuclei

Ques. 2JEE Main 2025, 3 April (Morning Shift)

Match the LIST-I with LIST-II Choose the correct answer from the options given below:

  1. A-II, B-I, C-III, D-IV
  2. A-III, B-I, C-II, D-IV
  3. A-III, B-I, C-IV, D-II
  4. A-II, B-I, C-IV, D-III
Ques. 3JEE Main 2025, 2 April (Evening Shift)

Energy released when two deuterons (1H2 ) fuse to form a helium nucleus (2He4 ) is : (Given : Binding energy per nucleon of 1H2 = 1.1 MeV and binding energy per nucleon of 2He4 = 7.0 MeV)

  1. 26.8 MeV
  2. 8.1 MeV
  3. 23.6 MeV
  4. 5.9 MeV
Ques. 4JEE Main 2025, 28 January (Morning Shift)

Choose the correct nuclear process from the below options [p : proton, n : neutron, e- : electron, e+ : positron, : neutrino, : antineutrino]

  1. n p + e+ +
  2. n p + e- +
  3. n p + e+ +
  4. n p + e- +
Ques. 5JEE Main 2025, 23 January (Morning Shift)

A radioactive nucleus n2 has 3 times the decay constant as compared to the decay constant of another radioactive nucleus n1. If initial number of both nuclei are the same, what is the ratio of number of nuclei of n2 to the number of nuclei of n1, after one half-life of n1 ?

  1. 1/4
  2. 1/8
  3. 4
  4. 8
Ques. 6JEE Main 2025, 23 January (Evening Shift)

Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R). In the light of the above statements, choose the correct answer from the options given below :

  1. (A) is true but (R) is false
  2. Both (A) and (R) are true and (R) is the correct explanation of (A)
  3. (A) is false but (R) is true
  4. Both (A) and (R) are true but (R) is NOT the correct explanation of (A)
Ques. 7JEE Main 2024, 9 April (Morning Shift)

The energy equivalent of 1 g of substance is :

  1. 5.6 1026 MeV
  2. 5.6 1012 MeV
  3. 5.6 eV
  4. 11.2 1024 MeV
Ques. 8JEE Main 2024, 9 April (Morning Shift)

A star has 100\% helium composition. It starts to convert three 4He into one 12C via triple alpha process as 4He + 4He + 4He 12C + Q. The mass of the star is 2.0 1032 kg and it generates energy at the rate of 5.808 1030 W. The rate of converting these 4He to 12C is n 1042 s-1, where n is . [Take, mass of 4He = 4.0026 u, mass of 12C = 12 u]

Ques. 9JEE Main 2024, 9 April (Evening Shift)

The energy released in the fusion of 2 kg of hydrogen deep in the sun is EH and the energy released in the fission of 2 kg of 235U is EU. The ratio EHEU is approximately: (Consider the fusion reaction as 4 11H + 2e- 24He + 2 + 6 + 26.7 MeV, energy released in the fission reaction of 235U is 200 MeV per fission nucleus and NA = 6.023 1023)

  1. 7.62
  2. 25.6
  3. 9.13
  4. 15.04
Ques. 10JEE Main 2024, 8 April (Morning Shift)

Binding energy of a certain nucleus is 18 108 J. How much is the difference between total mass of all the nucleons and nuclear mass of the given nucleus:

  1. 20 g
  2. 2 g
  3. 10 g
  4. 0.2 g
Ques. 11JEE Main 2024, 8 April (Evening Shift)

If M0 is the mass of isotope 125B, Mp and Mn are the masses of proton and neutron, then nuclear binding energy of isotope is:

  1. (5Mp + 7Mn - M0)C2
  2. (M0 - 5Mp - 7Mn)C2
  3. (M0 - 5Mp)C2
  4. (M0 - 12Mn)C2

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