Test: Nuclei (CBSE Level)


30 Questions MCQ Test Physics Class 12 | Test: Nuclei (CBSE Level)


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This mock test of Test: Nuclei (CBSE Level) for Class 12 helps you for every Class 12 entrance exam. This contains 30 Multiple Choice Questions for Class 12 Test: Nuclei (CBSE Level) (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Nuclei (CBSE Level) quiz give you a good mix of easy questions and tough questions. Class 12 students definitely take this Test: Nuclei (CBSE Level) exercise for a better result in the exam. You can find other Test: Nuclei (CBSE Level) extra questions, long questions & short questions for Class 12 on EduRev as well by searching above.
QUESTION: 1

What percentage of the mass of an atom is concentrated in the nucleus?

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QUESTION: 2

In the mass number range A = 30 to 170, the binding energy per nucleon is

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QUESTION: 3

Plutonium decays with a half-life of 24000 years. If the plutonium is stored for 72000 years, then the fraction of plutonium that remains is    

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QUESTION: 4

In a nuclear reaction which of the following is conserved

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QUESTION: 5

Cadmium rods are used in a nuclear reactor for

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In nuclear reactors, fission of uranium is carried out by bombarding  a slow moving neutron on uranium which results in emission of 3 more neutrons along with the byproducts  So, cadmium rods are used to absorb extra neutrons in order to achieve controlled chain reaction.

QUESTION: 6

In what units is mass measured on the atomic scale?

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QUESTION: 7

Energies associated with nuclear processes are

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QUESTION: 8

B210has a half life of 5 days. The time taken for seven-eighth of a sample to decay is

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QUESTION: 9

If 10% of a substance decays in 10 days, then approximate percentage of substance left after 24 days is

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QUESTION: 10

Choose the WRONG statement. A thermonuclear fusion reactor is better than a fission reactor for the following reason:

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QUESTION: 11

A free neutron decays into

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QUESTION: 12

The disintegration energy is

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QUESTION: 13

A radioactive substance has a half life of four months. Three fourths of the substance will decay in

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QUESTION: 14

At a given time there are 25% undecayed nuclei in a sample. After 10 seconds number of undecayed nuclei reduces to 12.5%. Then mean life of the nuclei will be about

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Half-life of radioactive sample, i.e., the time in which the number of undecayed nuclei becomes half (T) is 10 s.
Mean life, τ=T/loge​2=10s/0.693=1.443×10=14.43s ≈ 15s

QUESTION: 15

Which of the following particles can be added to the nucleus of an atom without changing its chemical properties?

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QUESTION: 16

Relation between atomic number (Z), neutron number (N) and mass number (A) is

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QUESTION: 17

α-rays are

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QUESTION: 18

The half life of radon is 3.8 days. After how many days will only one twentieth of a radon sample be left over?

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Let the initial amount of radon be N0​ and the amount left after t days be N which is equal to N0​/2

QUESTION: 19

90% of a radioactive sample is left undisintegrated after time τ has elapsed, what percentage of initial sample will decay in a total time 2τ?

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QUESTION: 20

The average number of neutrons released by the fission of one uranium atom is

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Fission also results in the production of several neutrons, typically two or three. On the average, about 2.5 neutrons are released per unit and the energy of a neutron released per fission of a uranium atom are 2 MeV. 

QUESTION: 21

The nuclei of isotopes of a given element contain the same number of

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QUESTION: 22

β -rays and γ-rays are respectively

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QUESTION: 23

Nuclear fusion is possible

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QUESTION: 24

What is the main source of energy of the sun?

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QUESTION: 25

All nuclides with same mass number A are called

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QUESTION: 26

When a hydrogen bomb explodes, which of the following is used?

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QUESTION: 27

The half-life T1/2of a radionuclide is

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QUESTION: 28

A radioactive material decays by simultaneous emission of two particles with respective half lives 1620 and 810 years. The time in years, after which one fourth of the material remains is

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Since, from Rutherford-Soddy law, the number of atoms left after half-lives is given by
N=N0​(1/2​)n
where, N0​ is the original number of atoms.
The number of half-lives, n= time of decay​/effective half−life
Relation between effective disintegration constant (λ) and half-life (T)
λ=ln2/T​
∴λ1​+λ2​= (​ln2/ T1​)+ ​(ln2/ T2​)
Effective half-life,
1/T​=1/T1​​+1/T2​​=(1/1620)​+(1/810)​
1/T​=1+2/1620 ​⇒T=540yr
∴n=T/540
∴N=N0​(1/2​)t/540⇒N/N0​​=(1/2​)2=(1/2​)t/540
⇒t/540​=2⇒t=2×540=1080yr

QUESTION: 29

The chemical behavior of an atom depends upon

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QUESTION: 30

Nuclear mass M is found to be

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