# Samacheer Kalvi 10th Science Solutions Chapter 6 Pdf

## Samacheer Kalvi 10th Science Solutions Chapter 6 Pdf

Tamilnadu Board Samacheer Kalvi 10th Science Solutions Chapter 6: Tamilnadu State Board Solution Class 10 Science Chapter 6 – Nuclear Physics.

### Samacheer Kalvi 10th Science Solutions Chapter 6: Overview

 Board Samacheer Kalvi Class 10 Subject Science Chapter 6 Chapter Name Nuclear Physics

### Samacheer Kalvi 10th Science Solutions Chapter 6 Nuclear Physics

d.) a & c

Ans:d. a & c

2.) Unit of radioactivity is _____________

a.) roentgen

b.) curie

c.) becquerel

d.) all the above

Ans:d. all the above

Explanation: Because, all above are the unit of radioactivity.

3) Artificial radioactivity was discovered by ____________

a.) Bequerel

b.) Irene Curie

c.) Roentgen

d.) Neils Bohr

Ans: b. Irene Curie

4.) In which of the following, no change in mass number of the daughter nuclei takes place

1. i) α decay
2. ii) β decay

iii) γ decay

1. iv) Neutron decay

a.) (i) is correct

b.) (ii) and (iii) are correct

c.) (i) & (iv) are correct

d.) (ii) & (iv) are correct

Ans:b. (ii) and (iii) are correct

Explanation: Because, beta and gamma particles are not having mass number.

5.) ____________ isotope is used for the treatment of cancer.

Explanation: Because, radio cobalt is used for the treatment of cancer.

6.) Gamma radiations are dangerous because

a.) it affects eyes & bones

b.) it affects tissues

c.) it produces genetic disorder

d.) it produces enormous amount of heat

Ans:c. it produces genetic disorder

Explanation: Because, they are having high penetrating power and high energetic.

7.) _____________ aprons are used to protect us from gamma radiations

b.) Iron

d.) Aluminium

Explanation: Because, lead acts as a shield which protect us from radiations.

8.) Which of the following statements is/are correct?

i.)     α particles are photons

ii.)    Penetrating power of γ radiation is very low

iii.) Ionization power is maximum for α rays

iv.)    Penetrating power of γ radiation is very high

a.) (i) & (ii) are correct

b.) (ii) & (iii) are correct

c.) (iv) only correct

d.) (iii) & (iv) are correct

Ans:d. (iii) & (iv) are correct

9.) Proton – Proton chain reaction is an example of __________________

a.) Nuclear fission

b.) α – decay

c.) Nuclear fusion

d.) β – decay

Ans:c. nuclear fusion

10.) in the nuclear reaction 6X12 α decay ZYA, the value of A & Z.

a.) 8, 6

b.) 8, 4

c.) 4, 8

d.) cannot be determined with the given data

Ans: c. 4, 8

Because, 6X12ZYA + 2α4, hence A= 4 and Z = 8.

11.) Kamini reactor is located at __________

a.) Kalpakkam

b.) Koodankulam

c.) Mumbai

d.) Rajasthan

Ans: a. Kalpakkam

12.) Which of the following is/are correct?

i.)     Chain reaction takes place in a nuclear reactor and an atomic bomb.

ii.)     The chain reaction in a nuclear reactor is controlled

iii.) The chain reaction in a nuclear reactor is not controlled

iv.) No chain reaction takes place in an atom bomb

a.) (i) only correct

b.) (i) & (ii) are correct

c.) (iv) only correct

d.) (iii) & (iv) are correct

Ans: b. (i) & (ii) are correct

II.) Fill in the blanks

1) One roentgen is equal to ____________ disintegrations per second

Ans:One roentgen is equal to 3.7*1010disintegrations per second

2) Positron is an____________.

Ans:  Positron is an antiparticle of electron.

3) Anemia can be cured by ____________ isotope

Ans:Anemia can be cured by radio iron Fe59isotope

4) Abbreviation of ICRP______

Ans: Abbreviation of ICRP International Commission on Radiological Protection.

5) _________is used to measure exposure rate of radiation in humans.

Ans: Roentgen is used to measure exposure rate of radiation in humans

6) ________ has the greatest penetration power.

Ans:Gamma ray has the greatest penetration power.

7.)  ZYA →   Z+1YA   + X; Then, X is __________

Ans:ZYA →   Z+1YA   + X; Then, X is-1e0 i.e. beta decay.

8) ZXA → ZYA This reaction is possible in ______________ decay.

Ans:ZXA → ZYA This reaction is possible in gammadecay.

9) The average energy released in each fusion reaction is about ________ J.

Ans:The average energy released in each fusion reaction is about 3.84*10-12J

10) Nuclear fusion is possible only at an extremely high temperature of the order of ____ K.

Ans:Nuclear fusion is possible only at an extremely high temperature of the order of 107 to 109K.

11) The radio isotope of ________ helps to increase the productivity of crops.

Ans: The radio isotope of phosphorous (P – 32) helps to increase the productivity of crops

12) If the radiation exposure is 100 R, it may cause ______________.

Ans:If the radiation exposure is 100 R, it may cause fatal disease.

III) State whether the following statements are true or false: If false, correct the statement

1) Plutonium -239 is a fissionable material.

Ans: True

2) Elements having atomic number greater than 83 can undergo nuclear fusion.

Ans: True

3) Nuclear fusion is more dangerous than nuclear fission.

Ans: False

Correct statement: Nuclear fission is more dangerous than nuclear fusion.

4) Natural uranium U-238 is the core fuel used in a nuclear reactor.

Ans: False

Correct statement: Natural uranium U -238 is not the fissile material and only fissile material are used in the fuel of nuclear reactor.

5) If a moderator is not present, then a nuclear reactor will behave as an atom bomb.

Ans: True

6) During one nuclear fission on an average, 2 to 3 neutrons are produced.

Ans: True

7) Einstein’s theory of mass energy equivalence is used in nuclear fission and fusion.

Ans: True

IV.) Match the following

Ans:

I:

1) BARC: Mumbai

2) India’s first atomic power station: Tarapur

3) IGCAR: Kalpkkam

4) The first nuclear reaction in India: Apsara

II:

1) Fuel: uranium

2) Moderator: graphite

3) Coolant: heavy water

III:

1) Soddy Fagan: Displacement law

4) Albert Einstein: Mass energy equivalence

IV:

1) Uncontrolled fission reaction: Atom bomb

2) Fertile material: breeder reactor

3) Controlled fission reaction: nuclear reactor

4) Fusion reaction: hydrogen bomb

V:

1) Co-60: Leukemia

2) I-30: Thyroid disease

3) Na-24: function of heart

4) C-14: age of fossil

V.) Arrange the following in the correct sequence:

1.) Arrange in descending order, on the basis of their penetration power Alpha rays, beta rays, gamma rays, cosmic rays

Ans:

The descending order on the basis of their penetration power is as follows:

1) Gamma rays

2) Beta rays

3) Alpha rays

4) Cosmic rays

2) Arrange the following in the chronological order of discovery Nuclear reactor, radioactivity, artificial radioactivity, discovery of radium.

Ans:

The chronological order of discovery is as follows:

4) Nuclear reactor – 1942

VI.) Use the analogy to fill in the blank

Ans:

2.) Nuclear Fusion: Extreme temperature, Nuclear Fission: Room temperature

3.) Increasing crops: Radio phosphorous, Effective functioning of heart: Radio sodium Na- 24

4.) Deflected by electric field: α ray, Null Deflection: Gamma ray

VII.) Numerical problems:

1) 88 Ra226 experiences three α – decay. Find the number of neutrons in the daughter element.

Ans:

Given that, 88 Ra226 experiences three α – decay

Hence,     88 Ra226→ X + 32α4

Thus, the atomic number of daughter element X is = 82

And mass number is Z = 214

Hence, number of neutrons in daughter element = 214 – 82 = 132.

2) A cobalt specimen emits induced radiation of 75.6 millicurie per second. Convert this disintegration in to Becquerel (one curie = 3.7 × 1010 Bq)

Ans:

Given that, cobalt specimen emits induced radiation of 75.6 mill curie per second.

But, 1 curie = 3.7*1010Bq

Hence, 75.6 mill curie per second = 75.6 * 10-3* 3.7*1010 Bq

= 279.72*107Bq

75.6 mill curie per second = 2.7972*109Bq

VIII.) Assertion and reason type questions: Mark the correct choice as

(a) If both the assertion and the reason are true and the reason is the correct explanation of the assertion.

(b) If both the assertion and the reason are true, but the reason is not the correct

explanation of the assertion.

(c) Assertion is true, but the reason is false.

(d) Assertion is false, but the reason is true.

1.) Assertion: A neutron impinging on U235, splits it to produce Barium and Krypton.

Reason: U – 235 is a fissile material.

Ans:(a) if both the assertion and the reason are true and the reason is the correct explanation of the assertion.

2.) Assertion: In a β – decay, the neutron number decreases by one.

Reason: In β – decay atomic number increases by one.

Ans:(d) Assertion is false, but the reason is true.

3.) Assertion: Extreme temperature is necessary to execute nuclear fusion.

Reason: In a nuclear fusion, the nuclei of the reactants combine releasing high energy.

Ans:(a) if both the assertion and the reason are true and the reason is the correct explanation of the assertion.

4.) Assertion: Control rods are known as ‘neutron seeking rods’

Reason: Control rods are used to perform sustained nuclear fission reaction

Ans:(a) if both the assertion and the reason are true and the reason is the correct explanation of the assertion.

IX.) Answer in one or two word (VSA)

Ans: Natural radioactivity was discovered by Henri Becquerel.

2.) Which radioactive material is present in the ore of pitchblende?

Ans: The radioactive material uranium is present in the ore of pitchblende.

3.) Write any two elements which are used for inducing radioactivity?

Ans: Boron, aluminum, alpha particle and neutron these elements are used for inducing radioactivity.

4.) Write the name of the electromagnetic radiation which is emitted during a natural radioactivity.

Ans: The electromagnetic radiation which is emitted during the natural radioactivity is gamma rays.

5.) If A is a radioactive element which emits an α – particle and produces 104Rf 259. Write the atomic number and mass number of the element A.

Ans: Let X be the radioactive element having atomic number Z and mass number A, which emits α – particle and 104Rf 259 which can be written in the reaction form as follows.

ZXA104Rf 259 + 2α4

Thus, to balance this nuclear reaction the atomic number must be 106 and mass number must be 263.

The element A has atomic number = 106

And mass number Z = 263

6.) What is the average energy released from a single fission process?

Ans: The average energy released during each fission process is about 3.2*10-11 J.

7) Which hazardous radiation is the cause for the genetic disease?

8) What is the amount of radiation that may cause death of a person when exposed to it?

Ans: The amount of radiation that may cause the death of a person when exposed to it is 600R.

9) When and where was the first nuclear reactor built?

Ans: The first nuclear reactor was built in 1942 at Chicago, USA.

10) Give the SI unit of radioactivity.

Ans: The SI unit of radioactivity is Becquerel.

11.) Which material protects us from radiation?

Ans: Lead metal acts as a radiation shielding material. While working in hazardous area we have to use lead aprons and lead gloves to protect us from radiation.

X.)  Answer the following questions in few sentences.

1.) Write any three features of natural and artificial radioactivity.

Ans:

• The phenomenon of spontaneous emission of radiations from the certain elements on their own is called as natural radioactivity.
• The elements having atomic number greater than 82 shows natural radioactivity.
• For example: uranium, radium etc.

• Artificial radioactivity is also induced in lighter elements.
• For example: boron, aluminum emits radiation when bombarded with alpha particles emitted in natural radioactivity.
• In artificial radioactivity, mostly elementary particles such as neutron, positrons etc are emitted.

2) Define critical mass.

Ans:

Critical mass:

The minimum mass of a fissile material which is necessary to sustain the nuclear chain reaction is called as critical mass.

Critical mass depends on nature, density and size of the fissile material.

3) Define one roentgen.

Ans:

One roentgen:

The amount of quantity of radioactive substance which produces a charge of 2.58*10-4 coulomb in 1 kg of air under the standard conditions of pressure, temperature and humidity is called as one roentgen.

4) State Soddy and Fajan’s displacement law.

Ans:

Soddy and Fajan discovered the displacement law which governs the daughter nucleus produced during the alpha and beta decay which are stated as follows:

1.) During the process of alpha decay, the daughter nucleus formed has mass number is less by 4 units and atomic number is less by 2 units than the mass and atomic number of parent nucleus.

2.) During the process of beta decay, the daughter nucleus formed has mass number is same as the parent nucleus and atomic number is more by 1 unit than the parent nucleus.

5) Give the function of control rods in a nuclear reactor.

Ans: Control rods in nuclear reactor are used to control number of neutrons in order to get sustain chain reaction.

Mainly boron or cadmium rods are used as control rods which absorbs the neutrons.

7) Mr. Ramu is working as an X – ray technician in a hospital. But, he does not wear the lead aprons. What suggestion will you give to Mr. Ramu?

Ans: I will suggest him to must wear apron because due to the exposing with x-rays there is harmful effects may cause on our body like destruction of WBCs, injury to tissues and skin also. Because x-ray are also high energy radiations.

8) What is stellar energy?

Ans: Stellar energy:

The large amount of energy emitted in the form of light and heat by the stars like our Sun, is called as stellar energy.

9) Give any two uses of radio isotopes in the field of agriculture?

Ans:

• The radioisotope of phosphorus P-32 is used to increase the productivity of crops.
• Also, the radiation emitted from isotopes are also used to kill insects, parasites and helps in preventing wastage of agricultural products.
• Also radiation prevents sprouting and spoilage of onions, potatoes and grams.

XI.) Answer the following questions in detail.

1) Explain the process of controlled and uncontrolled chain reactions.

Ans:

Controlled chain reaction:

• In controlled nuclear chain reaction, the number of neutrons released is only one. In this reaction, a neutron absorber absorbs the extra neutrons by leaving one neutron to produce further fission and in this way reaction is sustained in controlled manner.

• The energy released in controlled nuclear chain reaction is used for constructive purpose only.

• This type of reactions are used in nuclear reactors for producing energy in a sustained and controlled manner. Uncontrolled nuclear chain reaction:

• In uncontrolled nuclear chain reaction, the number of neutrons released are in multiple which are indefinite and causes the fission of fissile material in large amount.
• As a result, large amount of energy is released in a fraction of seconds.

2) Compare the properties of alpha, beta and gamma radiations.

Ans:

• Alpha rays:
• Alpha rays are the helium nuclei having two protons and two neutrons.
• Alpha particles are the positively charged particles with the charge of +2e.
• Alpha rays are having most ionizing power which is 100 time greater than beta rays and 10,000 times greater than gamma rays.
• The penetrating power of alpha rays is very low.
• Alpha rays get reflected by both electric and magnetic fields.
• The speed of alpha particles is in the range of 1/10 to 1/20 times speed of light.

2.) Beta particles:

• Beta particles are basic elementary particles i.e. electrons which are existing in all atoms.
• Beta particles are negatively charged with charge of -e.
• The ionizing power of beta particles is comparatively low.
• The penetrating power of beta particles is greater than alpha particles and they penetrate through thin metal foil.
• Beta rays are also deflected by both electric and magnetic field but their direction of deflection is opposite to the alpha particles.
• The speed of beta particles may go up to 9/10 times the speed of light.

3.) Gamma rays:

• These are the electromagnetic waves which are consisting of photons.
• Gamma rays are the neutral particles with the charge of zero.
• They are having very less ionising power.
• Gamma rays are having very high penetrating power greater than beta particles and they can penetrate through thick metal blocks also.
• As they are neutral in nature, they are not deflected by electric and magnetic fields.
• Gamma rays are the electromagnetic waves consisting of photons and travels with speed of light.

3.) What is a nuclear reactor? Explain its essential parts with their functions.

Ans:

Nuclear reactor:

Nuclear reactor is a device used to produce nuclear fission reaction which are in self-sustained and controlled manner to produce electricity.

Explanation of components of nuclear reactor:

The essential components of nuclear reactor are fuel, moderator, control rods, coolant and protection walls.

1.) Fuel: The fissionable materials are used as fuel in nuclear reactor and mainly uranium is used as fuel in nuclear reactors.

2.) Moderator: Moderator is used to slows down high energy neutrons in order to get slow neutrons.

Moderator used are graphite and heavy water.

3.) Control rods: Control rods are used to control the neutrons in order to get sustained chain reaction. Boron and cadmium rods are used as control rods which absorbs the neutrons.

4.) Coolant: It is used to reduce the heat generated in reactor core and to produce steam which is used to rotate the turbines and thereby electricity is generated. Water, air and helium are the coolants.

5.) Protection walls: Protection wall is the thick concrete lead wall which is developed around the nuclear reactor to prevent harmful radiations from escaping into the environment.

XII.) HOT Questions:

1) Mass number of a radioactive element is 232 and its atomic number is 90. When this element undergoes certain nuclear reactions, it transforms into an isotope of lead with a mass number 208 and an atomic number 82. Determine the number of alpha and beta decay that can occur.

Ans:

Given that, mass number A = 232

Atomic number Z = 90

After reaction forms isotope of lead with mass number A = 208

And atomic number Z = 82

Thus, the difference in mass number= 232 – 208 = 24

And difference in atomic number = 90 – 82 = 8

But, here both decays occurs alpha and beta.

Mass number of α = 4

Mass number of β = 0

Atomic number of α = 2

Atomic number of β = -1

Thus, number of α decay = difference in mass/ mass of α = 24/ 4 = 6

If 6 α-decay occurs then remaining will β decay which are 4 in number.

The following reaction explains these decays.

90X23282Pb208 + 62α4 + 4-1β0

2) ‘X – Rays should not be taken often’. Give the reason.

Ans:

Because X-rays are linked to risk of cancer and less short term effects.

The exposure to x-rays may cause loss of skin and hair, bleeding, vomiting, fainting etc which is very harmful to human body. That’s why x-rays should not be taken often

3) Cell phone towers should be placed far away from the residential area – why?

Ans:

Cell phone towers should be placed far away from the residential areas because they communicate by using radio frequency radiation with each other. That may cause harmful effects on human body.  If cellphone towers are near to residential area then it may very risky, due to which they are constructed far away from the residential area.

Updated: July 3, 2021 — 6:40 pm