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# Selina solutions for Concise Physics Class 10 ICSE chapter 12 - Radioactivity [Latest edition]

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#### Chapters Exercise - 12 (A)Exercise - 12 (B)

### Selina solutions for Concise Physics Class 10 ICSE Chapter 12 Radioactivity Exercise - 12 (A) [Pages 297 - 300]

Exercise - 12 (A) | Q 1 | Page 297

Name the three constituent of an atom and state their mass and charge of each. How are they distributed in an atom?

Exercise - 12 (A) | Q 2.1 | Page 297

Define the term : Atomic number

Exercise - 12 (A) | Q 2.2 | Page 297

Define the term : mass number.

Exercise - 12 (A) | Q 3 | Page 297

What is nucleus of an atom? Compare its size with that of the atom. Name its constitutents. How is the number of these constituents determined by the atomic number its atomic model.

Exercise - 12 (A) | Q 4 | Page 297

State the atomic number and mass number of  $\ce{^23_11Na}$  and draw its atomic model.

Exercise - 12 (A) | Q 5 | Page 297

What are isotopes? Give one example.

Exercise - 12 (A) | Q 6 | Page 297

What are isobars? Give one example.

Exercise - 12 (A) | Q 7 | Page 297

Name the atoms of a substance having same atomic number, but different mass numbers. Give one example of such a substance. How do the structures of such atoms differ?

Exercise - 12 (A) | Q 8 | Page 297

Exercise - 12 (A) | Q 9 | Page 297

Exercise - 12 (A) | Q 10.1 | Page 297

Exercise - 12 (A) | Q 10.2 | Page 297

Name the radiations which are deflected by the electric field.

Exercise - 12 (A) | Q 10.3 | Page 297

Name the radiation which is most penetrating.

Exercise - 12 (A) | Q 10.4 | Page 297

Name the radiation which travels with the speed of light.

Exercise - 12 (A) | Q 10.5 | Page 297

Name the radiation which has the highest ionizing power.

Exercise - 12 (A) | Q 10.6 | Page 297

Name the radiation consisting of the same kind of particles as the cathode rays.

Exercise - 12 (A) | Q 11 | Page 297

(a) Which radiation has zero mass?

(b) Name the radiation which has the lowest ionizing power.

(c) Name the radiation which has the lowest penetrating power.

(d) Give the charge and mass of particles composing the radiation in part (c).

(e) When the particle referred to in part (c) becomes neutral, they are found to be the atoms of rare gas. Name this rare gas and draw a model of its neutral atom.

(f) From which part of the atom do these radiations come?

Exercise - 12 (A) | Q 12 | Page 298

The diagram in figure shows a radioactive source S placed in a thick lead walled container. The radiations given off are allowed to pass through a magnetic field. The magnetic field (shown as x) acts perpendicular to the plane of paper inwards. Arrows shows the paths of the radiation A, B and C. (a) Name the radiations labelled A, B and C.

(b) Explain clearly how you used the diagram to arrive at the answer in part(a).

Exercise - 12 (A) | Q 13 | Page 298

In following Figure shows a mixed source R of alpha and beta particles in a thick lead walled container.

The particles pass through a magnetic field in a direction perpendicular to the plane of paper inwards as shown by x.

(a) Show in the diagram how the particles get affected.

(b) Name the law used in part (a) [Hint: Alpha particles will deflect to the left while beta particles to the right]

Exercise - 12 (A) | Q 14 | Page 298

In following Figure shows a radioactive source S in a thick lead walled container having a narrow opening. The radiations pass through an electric field between the plates A and B. (a) Complete the diagram to show the paths of α , β and γ radiations.

(b) Why is the source S kept in a thick lead walled container with a narrow opening?

(c) Name the radiation which is unaffected by the electrostatic field.

(d) Which radiation is defleced the most. Given reason.

(e) Which among the three radiations causes the least biological damage?

Exercise - 12 (A) | Q 15 | Page 298

Explain why alpha and beta particles are deflected in an electric or a magnetic field, but gamma rays are not deflected in such a field.

Exercise - 12 (A) | Q 16 | Page 298

Is it possible to deflect  γ - radiations in a way similar to α and β -particles, using the electric or magnetic field ? Give reasons.

Exercise - 12 (A) | Q 17 | Page 298

State following four properties each of α , β and γ radiations: (a) Nature, (b) Charge, (c) Mass and (d) Effect of electric field.

Exercise - 12 (A) | Q 18 | Page 298

Arrange the α, β, or γ raditions in ascending order of their (i) ionising powers, and (ii) penetrating powers.

Exercise - 12 (A) | Q 19 | Page 298

State the speed of each of α , β and γ - radiations.

Exercise - 12 (A) | Q 20.1 | Page 298

What is the composition of α , β and γ -radiations?

Exercise - 12 (A) | Q 20.2 | Page 298

Which one has the least penetrating power?

Exercise - 12 (A) | Q 21 | Page 298

How γ - radiations are produced? Mention two common properties of gamma radiations and visible light.

Exercise - 12 (A) | Q 22 | Page 298

An α - -particle captures
(i) one electron,
(ii) two electrons.
In each case, What does it change to?

Exercise - 12 (A) | Q 23 | Page 298

'Radioactivity is a nuclear phenomenon'. Comment on this statement.

Exercise - 12 (A) | Q 24 | Page 298

What kind of change takes place in a nucleus when a  β - particle is emitted? Express it by an equation. State whether
(a) atomic number and
(b) mass number are conserved in a radioactive β - decay ?

Exercise - 12 (A) | Q 25 | Page 298

A certain radioactive nucleus emits a particle that leaves its mass unchanged, but increased its atomic number by one. Identify the particle and write its symbol.

Exercise - 12 (A) | Q 26 | Page 298

What happens to the (i) atomic number, (ii) mass number of an element when (a) α - particle (b) β -particle and (c) γ -radiation are emitted?

Exercise - 12 (A) | Q 27 | Page 298

What happens to the position of an element in the periodic table when it emits an alpha particle

Exercise - 12 (A) | Q 28 | Page 299

What changes occurs in the nucleus of radioactive elements when it emits (a) an alpha particle (b) beta particle and (c) gamma radiations? Give one example in each case in support of your answer.

Exercise - 12 (A) | Q 29 | Page 299

(a)An atomic nucleus A is composed of 84 protons and 128 neutrons. The nucleus A emits an α -particle and is transformed into a nucleus B. What is the composition of B?

(b)The nucleus B emits a β -particle and is transformed into a nucleus C. What is the composition of C?

(c)What is the mass number of nucleus A?

(d)Does the composition of nucleus C change if it emits a γ  -radiation?

Exercise - 12 (A) | Q 30.1 | Page 299

A certain nucleus A (mass number 238 and atomic number 92) is radioactive and becomes a nucleus B (mass number 234 and atomic number 90) by the loss of one particle.

What particle was emitted?

Exercise - 12 (A) | Q 30.2 | Page 299

A certain nucleus A (mass number 238 and atomic number 92) is radioactive and becomes a nucleus B (mass number 234 and atomic number 90) by the loss of one particle.

Exercise - 12 (A) | Q 30.3 | Page 299

A certain nucleus A (mass number 238 and atomic number 92) is radioactive and becomes a nucleus B (mass number 234 and atomic number 90) by the loss of one particle.

State the change in the form of a reaction.

Exercise - 12 (A) | Q 31.1 | Page 299

State whether the following nuclear disintegration are allowed or not (star indicate an exited state). Give reason if it is not allowed.

$\ce {^A_Z X^* -> ^A_ZX + γ}$

Exercise - 12 (A) | Q 31.2 | Page 299

State whether the following nuclear disintegration are allowed or not (star indicate an exited state). Give reason if it is not allowed.

$\ce{^A_Z X -> ^A_{Z-2} X + ^4_2 He}$

Exercise - 12 (A) | Q 32.1 | Page 299

A nucleus is $\ce {^24_11 Na}$  is  β-radioactive.

What are the numbers 24 and 11 called ?

Exercise - 12 (A) | Q 32.2 | Page 299

A nucleus is  $\ce{^24_11 Na}$  β-radioactive.

Write the equation represent β-decay.

Exercise - 12 (A) | Q 32.3 | Page 299

A nucleus is $\ce {^24_11 Na}$  β-radioactive.

What general name is given to the product nucleus with respect to  $\ce {^24_11 Na}$ ?

Exercise - 12 (A) | Q 33.1 | Page 299

A nucleus of stable phosphorus has 15 protons and 16 neutrons.

What is its atomic number and mass number.

Exercise - 12 (A) | Q 33.2 | Page 299

A nucleus of stable phosphorus has 15 protons and 16 neutrons.

The nucleus of radio phosphorous has one neutron more than the stable nucleus. What will be its atomic number and mass number?

Exercise - 12 (A) | Q 33.3 | Page 299

A nucleus of stable phosphorus has 15 protons and 16 neutrons.

What will be the atomic number and mass number of new nucleus formed by decay of a β-particle by the radio phosphorus in part(b)?

Exercise - 12 (A) | Q 34 | Page 299

An element P disintegrates by α - -emission and the new element suffers two further disintegrations, both by β -emission, to form an element Q. Explain the fact that P and Q are the isotopes.

Exercise - 12 (A) | Q 35 | Page 299

A nucleus $\ce {^A_Z X}$ emits 2 α particles and 1 β particles to form a nucleus $\ce {^222_85 R}$. Find the atomic nucleus and mass number of X.

Exercise - 12 (A) | Q 36.1 | Page 299
The mass number (A) of an element is not changed when it emits ______________.
Exercise - 12 (A) | Q 36.2 | Page 299

The atomic number of a radioactive element is not changed when it emits ............

Exercise - 12 (A) | Q 36.3 | Page 299

Complete the following sentence :

During the emission of a beta particle, the ________ number remains same.

Exercise - 12 (A) | Q 37.1 | Page 300

Complete the following nuclear change :

$\ce {^a_x P -> Q + ^0_-1 β}$

Exercise - 12 (A) | Q 37.2 | Page 300

Complete the following nuclear change :

$\ce {^238_92 U -> ^234_90 Th + .... + Energy}$

Exercise - 12 (A) | Q 37.3 | Page 300

Complete the following nuclear change :

$\ce {^238_92 P \text ->[α] Q \text ->[β] R \text ->[β] S}$

Exercise - 12 (A) | Q 37.4 | Page 300

Complete the following nuclear change :

$\ce {^A_Z X \text ->[α] X_1 \text ->[γ] X_2 \text ->[2β] X_3}$

Exercise - 12 (A) | Q 37.5 | Page 300

Complete the following nuclear changes:

$\ce {X \text ->[β] X_1 \text ->[α] X_2 \text ->[α] ^172_69 X_3}$

Exercise - 12 (A) | Q 38 | Page 300

What are radio isotopes? Give one example of a radio isotope. State one use of radio isotopes.

Exercise - 12 (A) | Q 39 | Page 300

Why are the alpha particles not used in radio therapy?

Exercise - 12 (A) | Q 40 | Page 300

Why do we usually use isotopes emitting gamma radiations as radioactive tracers in medical science?

Exercise - 12 (A) | Q 41 | Page 300

When does the nucleus of an atom become radioactive?

Exercise - 12 (A) | Q 42.1 | Page 300

Which of the following is the radio isotope in  pair ?

$\ce {^12_6 C , ^14_6 C}$

Exercise - 12 (A) | Q 42.2 | Page 300

Which of the following is the radio isotope in pair?

$\ce {^30_15 P , ^32_15 P}$

Exercise - 12 (A) | Q 42.3 | Page 300

Which of the following is the radio isotope in pair ?

$\ce {^39_19 K , ^40_19 K}$

Exercise - 12 (A) | Q 43 | Page 300

State the medical use of radioactivity.

Exercise - 12 (A) | Q 44 | Page 300

Arrange the α, β, and γ radiation in ascending order of their biological damage. Give reason.

Exercise - 12 (A) | Q 45 | Page 300

Name two main sources of nuclear radiations. How are these radiations harmful?

Exercise - 12 (A) | Q 46 | Page 300

State two safety measures to be taken while establishing a nuclear power plant?

Exercise - 12 (A) | Q 47.1 | Page 300

What is meant by nuclear waste?

Exercise - 12 (A) | Q 47.2 | Page 300

Suggest one effective way for the safe disposal of nuclear waste.

Exercise - 12 (A) | Q 48 | Page 300

State three safety precautions that you would take while handling the radioactive substances.

Exercise - 12 (A) | Q 49 | Page 300

Why should a radioactive substance not be touched by hands?

Exercise - 12 (A) | Q 50 | Page 300
What do you mean by background radiations? Name its sources. Is it possible for us to keep ourselves away from it?

### Selina solutions for Concise Physics Class 10 ICSE Chapter 12 Radioactivity Exercise - 12 (A) [Page 300]

Exercise - 12 (A) | Q 1 | Page 300

• α , β and γ simultaneously

• In the order α , β and γ one by one

• X-ray and Y-ray

• α  or  β

Exercise - 12 (A) | Q 2 | Page 300

In β- emission from a radioactive substance, an electron is ejected. This electron comes from:

• The outermost orbit of an atom

• The inner orbits of an atom

• The surface of substance

• The nucleus of an atom

Exercise - 12 (A) | Q 3 | Page 300

• α - particles

• β - particles

• X - rays

Exercise - 12 (A) | Q 4 | Page 300

The radiation suffering the maximum deflection in a magnetic field is:

• α - particles

• β - particles

• X - rays

### Selina solutions for Concise Physics Class 10 ICSE Chapter 12 Radioactivity Exercise - 12 (B) [Pages 306 - 307]

Exercise - 12 (B) | Q 1 | Page 306

What do you mean by nuclear energy? What is responsible for its release?

Exercise - 12 (B) | Q 2 | Page 306

Write down the Einstein's mass-energy equivalence relation, explaining the meaning of each symbol used in it.

Exercise - 12 (B) | Q 3.1 | Page 306

What is a.m.u ? Express 1 a.m.u. in MeV.

Exercise - 12 (B) | Q 3.2 | Page 306

Write the approximate mass of a proton, neutron and electron in a.m.u.

Exercise - 12 (B) | Q 4 | Page 306

What is nuclear fission? Name the particle used for it. Write one fission reaction.

Exercise - 12 (B) | Q 5 | Page 306

Name two isotopes of uranium.

Which of the isotope mentioned in part (a) above is easily fissionable? Give reason.

State whether the neutron needed for fission reaction of the isotope mentioned in part (b) above, is slow or fast?

Exercise - 12 (B) | Q 6 | Page 306

Write the approximate value of the energy released in the fission of one nucleus of $\ce {^235_92 U}$ . What is the reason for it?

Exercise - 12 (B) | Q 7.1 | Page 306

Complete the following nuclear fission reaction.

$\ce{^235_92 U + ^1_0n ->_56Ba + ^92Kr + 3 ^1_0 n + ....}$

Exercise - 12 (B) | Q 7.2 | Page 306

Complete the following nuclear fission reaction.

$\ce {^235_92 U + ^1_0n -> ^148 La + ^85_35 Br + ....^1_0n + Energy}$

Exercise - 12 (B) | Q 8 | Page 306

What do you mean by the chain reaction in nuclear fission ? How is it controlled ?

Exercise - 12 (B) | Q 9 | Page 306

State two uses of nuclear fission.

Exercise - 12 (B) | Q 10 | Page 306

Give two differences between the radioactive decay and nuclear fission.

Exercise - 12 (B) | Q 11.1 | Page 306

What is nuclear fission? Give one example and write its nuclear reaction.

Exercise - 12 (B) | Q 11.2 | Page 306

What other name is given to nuclear fusion? Give reason.

Exercise - 12 (B) | Q 12 | Page 306

Why is a very high temperature required for the process of nuclear fusion? State the approximate temperature required.

Exercise - 12 (B) | Q 13 | Page 307

(a) Write one nuclear fusion reaction.

(b) State the approximate value of energy released in the reaction mentioned in part (a).

(c) Give reason for the release of energy stated in part (b).

Exercise - 12 (B) | Q 14.1 | Page 307

Complete the following fusion reaction :

$\ce {^3_2He + ^2_1H -> _2He + _1H + energy}$

Exercise - 12 (B) | Q 14.2 | Page 307

Complete the following fusion reaction :

$\ce {^2_1H + ^2_1H -> _2He + ^1H + energy}$

Exercise - 12 (B) | Q 15.1 | Page 307

Name the process, nuclear fission or nuclear fusion, in which the energy released per unit mass is more?

Exercise - 12 (B) | Q 15.2 | Page 307

Name the process, fission or fusion which is possible at ordinary temperature.

Exercise - 12 (B) | Q 16.1 | Page 307

State the similarity in the process of nuclear fission or fusion

Exercise - 12 (B) | Q 16.2 | Page 307

State two difference between the process of nuclear fission or fusion.

Exercise - 12 (B) | Q 17 | Page 307

Give two examples of nuclear fusion.

Exercise - 12 (B) | Q 18 | Page 307

What is the source of energy of Sun or stars?

Exercise - 12 (B) | Q 19.1 | Page 307

Name the following nuclear reaction :

$\ce {^235_92U +^1_0-> ^90_38Sr + ^143_54Xe + 3^1_0n + γ}$

Exercise - 12 (B) | Q 19.2 | Page 307

Name the following nuclear reaction :

$\ce {^3_1H + ^2_1H -> ^4_2He + ^1_0n + γ}$

### Selina solutions for Concise Physics Class 10 ICSE Chapter 12 Radioactivity Exercise - 12 (B) [Page 307]

Exercise - 12 (B) | Q 1 | Page 307

The particle used in nuclear fission for bombardment is :

• Alpha particle

• Proton

• Beta particle

• neutron

Exercise - 12 (B) | Q 2 | Page 307

The temperature required for the process of nuclear fusion is nearly:

• 1000 K

• 104K

• 105K

• 107K

### Selina solutions for Concise Physics Class 10 ICSE Chapter 12 Radioactivity Exercise - 12 (B) [Page 307]

Exercise - 12 (B) | Q 1 | Page 307

In fission of one uranium - 235 nucleus, the loss in mass is 0.2 a.m.u. Calculate the energy released.

Exercise - 12 (B) | Q 2 | Page 307

When four hydrogen nuclei combine to form a helium nucleus in the interior of sun, the loss in mass is 0.0265 a.m.u. How much energy is released ?

Exercise - 12 (A)Exercise - 12 (B) ## Selina solutions for Concise Physics Class 10 ICSE chapter 12 - Radioactivity

Selina solutions for Concise Physics Class 10 ICSE chapter 12 (Radioactivity) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CISCE Concise Physics Class 10 ICSE solutions in a manner that help students grasp basic concepts better and faster.

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Concepts covered in Concise Physics Class 10 ICSE chapter 12 Radioactivity are Radioactivity and Changes in the Nucleus, Concept of Nuclear Fission and Fusion;, Radiation, Nuclear Energy, Heat - Latent Heat, Energy Sources, Different Types of Energy.

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