NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET

NEET: NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET

The document NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET is a part of the NEET Course Physics Class 12.
All you need of NEET at this link: NEET

Q.1. A nucleus with mass number 240 breaks into fragments each of mass number 120, the binding energy per nucleon of unfragmented nuclei is 7.6 MeV while that of fragments is 8.5 MeV. The total gain in the Binding Energy in the process is:    (2021)
A: 804 MeV
B: 216 MeV
C: 0.9 MeV
D: 9.4 MeV
Ans: 
B
Solution:

NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET
Given binding energy per nucleon of X, Y & Z are 7.6 MeV, 8.5 MeV & 8.5 MeV respectively.
Gain in binding energy is :-
Q = Binding Energy of products – Binding energy of reactants
= (120 × 8.5 × 2) – (240 × 7.6) MeV
= 216 MeV

Q.2. A radioactive nucleus NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET undergoes spontaneous decay in the sequence
NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEETWhere Z is the atomic number of element X. The possible decay particles in the sequence are :     (2021)
A:  β+,α,β-
B: β-,α,β+

C: α,β-+
D: α,β+- 
Ans: 
A
Solution:

NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET
β+ decreases atomic number by 1
α decreases atomic number by 2
β- decreases atomic number by 1

Q.3. The half-life of a radioactive nuclide is 100 hours. The fraction of original activity that will remain after 150 hours would be:     (2021)
A: 2/3
B: 2/3√2
C: 1/2
D: 1/2√2

Ans: D
Solution:

NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET

Q.4. The energy equivalent of 0.5 g of a substance is :     (2020)
A: 1.5×1013 J
B: 0.5×1013J
C: 4.5×1016J
D: 4.5×1013J

Ans: D
Solution:
E = Δmc2 = 0.5 × 10-3 × (3 × 108)2 
= 0.5 ×10-3 × 9 ×1016
E = 4.5 ×1013 J

Q.5. When a uranium isotopeNEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEETis bombarded with a neutron, it generates NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEETthree neutrons and :      (2020)
A:
NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET
B:
NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET
C:
NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET
D:
NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET

Ans: C
Solution: 
NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET
92 = 36 + Z; ← A + 89 + 3 = 235 ⇒ A = 144
Z = 56

Q.6. For a radioactive material, half-life is 10 minutes. If initially there are 600 number of nuclei, the time taken (in minutes) for the disintegration of 450 nuclei is:    (2018)
A: 20
B: 10
C: 30
D: 15
Ans: 
A
Solution:
NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET
NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET


Q.7. Radioactive material 'A' has decay constant '8 λ' and material 'B' has decay constant 'λ'. Initially they have same number of nuclei. After what time, the ratio of number of nuclei of material 'B' to that 'A' will be 1/e?     (2017)
A: 1/7λ
B: 1/8λ
C: 1/9λ
D: 1/10λ
Ans: A
Solution:

NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET
NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET
NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET

Q.8. The Binding energy per nucleon of NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET nuclei are 5.60 MeV and 7.06 MeV, respectively. In the nuclear reaction NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET the value of energy Q released is :    (2014)
A: 8.4 MeV
B: 17.3 MeV
C: 19.6 MeV
D: −2.4 MeV
Ans: B
Solution:

NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET
NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET
NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET

Q.9. A radio isotope ‘X’ with a half life 1.4 × 109 years decays to ‘Y’ which is stable. A sample of the rock from a cave was found to contain ‘X’ and ‘Y’ in the ratio 1 : 7. The age of the rock is    (2014)
A: 4.20 × 109 years
B: 8.40 × 109 years
C: 1.96 × 109 years
D: 3.92 × 109 years
Ans: A
Solution:

Ratio of X:Y is given = 1:7
That is,
NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET
⇒ 7mx = my
Let, the initial total mass is m.
NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET
Therefore, time taken to become 1/8 unstable part
= 3 x T1/2
= 3 x 1.4 x 109
= 4.2 x 109 y

The document NEET Previous Year Questions (2014-21): Nuclei Notes | Study Physics Class 12 - NEET is a part of the NEET Course Physics Class 12.
All you need of NEET at this link: NEET
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