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

#### Chapters Exercise 12 (A)Exercise 12 (B)
Exercise 12 (A) [Pages 297 - 300]

### 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?
Exercise 12 (A) [Page 300]

### 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

Exercise 12 (B) [Pages 306 - 307]

### 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 :

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

Exercise 12 (B) [Page 307]

### 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

Exercise 12 (B) [Page 307]

### 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 Nuclear Energy, Radiation, Safety Precautions While Using Nuclear Energy, Nuclear Fission, Nuclear Fusion, Distinction Between the Radioactive Decay and Nuclear Fission, Distinction Between the Nuclear Fission and Nuclear Fusion, Atoms: Building Blocks of Matter, Structure of an Atom, Discovery of Charged Particles in Matter, Nucleus, Atomic Mass, Atomic Number (Z), Mass Number (A), and Number of Neutrons (n), Isotopes, Isobars, Isotones or Isoneutronic, Radioactivity, Radioactivity as Emission of Alpha, Beta, and Gamma Radiations, Properties of Alpha Particles, Properties of Beta Particles, Properties of Gamma Radiations, Changes Within the Nucleus in Alpha, Beta and Gamma Emission, Alpha Decay (Alpha Emission), Beta Decay (Beta Emission), Gamma Decay (Gamma Emission), Uses of Radioactivity.

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