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Nuclei · Question 1

NEET (UG) 2026MCQEasy📈 Topic in 25% papers+4−1
1

Four statements are given (A is mass number) : Choose the correct answer from the options given below :

  1. A and D are true, but B and C are false
  2. B and D are true, but A and C are false
  3. B and C are true, but A and D are false
  4. A and C are true, but B and D are false

Answer

(2) B and D are true, but A and C are false

Solution

As per NCERT, R = R0A1/3

V = 43 R3 = 43 R03A

V A ⇒ statement A is false and statement B is true.

Mass of an atom − mass of its nucleus = mass of its electrons; this is not the mass defect ⇒ statement C is false.

As per NCERT, mass defect M = [Zmp + (A - Z)mn] - M, the difference between the mass of the constituent nucleons and the mass of the nucleus ⇒ statement D is true.

B and D are true, but A and C are false.

Answer: (2)

NEET (UG) 2026

Keep practising — Nuclei

2

An unknown nucleus has a nuclear density of 2.29 1017 kg/m3 and mass of 19.926 10-27 kg. Its mass number A is approximately : (Take R0 = 1.2 10-15 m, 4π = 12.56)

  1. 16
  2. 20
  3. 12
  4. 19
NEET (UG) 2026
3

Consider the following nuclear reaction 238U 234Th + 4He Take masses of 238U, 234Th and 4He as 238.050 u, 234.043 u and 4.003 u, respectively. The Q value for the reaction, in keV, is: [Given: 1 u = 931.5 MeV c-2]

  1. 3740
  2. 3726
  3. 3730
  4. 3736
RE-NEET (UG) 2026
4

29082X Y e+ Z - P e- Q In the nuclear emission stated above, the mass number and atomic number of the product Q respectively, are

  1. 280, 81
  2. 286, 80
  3. 288, 82
  4. 286, 81
NEET (UG) 2024
5

Water is used as a coolant in a nuclear reactor because of its

  1. high thermal expansion coefficient
  2. high specific heat capacity
  3. low density
  4. low boiling point
RE-NEET (UG) 2024
6

Select the correct statements among the following : Choose the most appropriate answer from the options given below :

  1. A, B and C only
  2. A, B and D only
  3. A and B only
  4. C and D only
RE-NEET (UG) 2024
7

The half life of a radioactive substance is 20 minutes. In how much time, the activity of substance drops to ( 116 )th of its initial value?

  1. 40 minutes
  2. 60 minutes
  3. 80 minutes
  4. 20 minutes
Out of syllabusNEET (UG) 2023
8

A nucleus of mass number 189 splits into two nuclei having mass number 125 and 64. The ratio of radius of two daughter nuclei respectively is

  1. 1 : 1
  2. 4 : 5
  3. 5 : 4
  4. 25 : 16
NEET (UG) 2022
9

In the given nuclear reaction, the element X is 2211Na X + e+ +

  1. 2311Na
  2. 2310Ne
  3. 2210Ne
  4. 2212Mg
Out of syllabusNEET (UG) 2022
10

Given below are two statements In the light of the above statements, choose the most appropriate answer from the options given below :

  1. Statement I is incorrect but statement II is correct
  2. Both statement I and statement II are correct
  3. Both statement I and statement II are incorrect
  4. Statement I is correct but statement II is incorrect
Out of syllabusNEET (UG) 2022 (Phase 2)
11

At any instant, two elements X1 and X2 have same number of radioactive atoms. If the decay constant of X1 and X2 are 10 and respectively, then the time when the ratio of their atoms becomes 1e respectively will be :

  1. 15
  2. 111
  3. 19
  4. 16
Out of syllabusNEET (UG) 2022 (Phase 2)

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