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Theory For Notes Making

Objective Assignment

Subjective Assignment

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Theory For Notes Making

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Objective Assignment

1.

The energy of neutron in thermal equilibrium at room temperature is approximately

(a) 5 eV   

(b) 1 eV   

(c) 0.1 eV

(d) 0.025 eV.

Ans  (d)

2.

1 milligram radium has 2.68 × 1018 nuclei. Its half-life is 1620 year. After 3240 year, how many nuclei would have disintegrated?

(a) 1.82 × 1018                               

(b) 1.34 × 1018                                               

(c) 0.67 × 1018                                

(d) 2.01 × 1018.

Ans (d)

3.

Fast neutrons can easily be slowed down by

(a) the use of lead shielding           

(b) passing them through heavy water

(c) elastic collision with heavy nuclei                                           

(d) applying strong magnetic field.

Ans  (b)

4.

What percentage of a radioactive substance is left after 5 half-live

(a) 31%    

(b) 3.12%

(c) 0.3%   

(d) 1%

Ans (b)

5.

Radon has 3.8 day as its half-life. How much radon will be left out of 15 mg mass after 38 day?

(a) 1.515 mg

(b) 0.015 mg

(c) 1.049 mg

(d) 9.327 mg

Ans (b)

Subjective Assignment

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QUIZ

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Created on By physicscart

Binding Energy Curve, Nuclear Force, Introduction Of Radioactivity (Basic Level)

1 / 10

The fraction f of radioactive material that has decayed in time t, varies with time t. The correct variation is given by the curve

2 / 10

A radioactive sample is $latex \displaystyle \alpha $-emitter with half life 138.6 days is observed by a student to have 2000 disintegration/sec. The number of radioactive nuclei for given activity are

3 / 10

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

4 / 10

The half life of radioactive Radon is 3.8 days. The time at the end of which 1/{{20}^{{th}}}of the Radon sample will remain undecayed is  (Given 1/{{20}^{{th}}})

5 / 10

Half-life of a radioactive substance is 20 minutes. Difference between points of time when it is 33% disintegrated and 67% disintegrated is approximately

6 / 10

In a radioactive substance at t=0, the number of atoms is 8\times {{10}^{4}}. Its half life period is 3 years. The number of atoms 1\times {{10}^{4}} will remain after interval

7 / 10

Alpha rays emitted from a radioactive substance are

8 / 10

What percentage of original radioactive atoms is left after five half lives

9 / 10

A freshly prepared radioactive sample of half- life 1 hour emits radiations that are 128 times as intense as the permissible safe limit. The minimum time after which this sample can be safely used is

10 / 10

A radioactive nucleus undergoes $latex \displaystyle \alpha $-emission to form a stable element. What will be the recoil velocity of the daughter nucleus if V is the velocity of $latex \displaystyle \alpha $-emission and A is the atomic mass of radioactive nucleus

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