Selina Concise Class 10 Physics Solution Chapter No. 12 – ‘Radioactivity’ For ICSE Board Students.
Selina Concise Class 10 Physics Chapter 12 Radioactivity Exercise All Questions and Answers by Physics Teacher here in this post.
Exercise 12 (A)
Question: 1
Name the three constituents of an atom and state mass and charge of each. How are they distributed in an atom?
Solution: Three constituents of an atom are protons, electrons and neutrons. Proton has mass of 1.6726 x 10-27 kg and charge on proton is +1.6 x 10-19 C. Electron has mass of 9.1 x 10-31 kg and charge of -1.6 x 10-19 C. Neutron has mass of 1.6726 x 10-27 kg and charge is zero. The protons and neutrons are present in the nucleus of atom and electrons are revolving around the nucleus.
Question: 2
Define the following terms:
(a) Atomic number and (b) mass number.
Solution:
a.) Number of protons in an atoms nucleus is called as atomic number.
b.) The total number of nucleons that is protons and neutrons is called mass number.
Question: 3
What is the nucleus of an atom? Compare its size with that of the atom. Name its constituents. How is the number of these constituents determined by the atomic number and mass number of an atom?
Solution: The centre of atom is called as nucleus. Nucleus size is 10-5 to 10-4 times the size of atom. The nucleus consists of protons and neutrons. Atomic number of atomis number of protons and atomic mass number is sum of number of protons and nucleus.
Question: 4
State the atomic number and mass number of 23Na11 draw its atomic model.
Solution: Atomic number of sodium = 11
Mass number of sodium = 23
Question: 5
What are isotopes? Give one example.
Solution: when a atom of same element has same atomic number but different in the mass number of atom is called isotopes. For example,hydrogen has three isotopes. 1H1, 2H1 and 3H1.
Question: 6
What are isobars? Give one example.
Solution: the atoms of different elements which have the same mass number are called as isobars. For example, 40Ar18, 40K19 and 40Ca20.
Question: 7
What is the name given to elements with same mass number and different atomic number
Solutions: isobars
Question: 8
Name the atoms of a substance having the same atomic number, but different mass numbers. Give one example of such a substance. How do the structures of such atoms differ?
Solution: When an atom of same element has same atomic number but different in the mass number of atom is called isotopes. For example, hydrogen has three isotopes. 1H1, 2H1 and 3H1. The structure differs with change in structure of nucleus.
Question: 9
What is meant by radioactivity? Name two radioactive substances.
Solution: The process of spontaneous emission of certain radiation from nuclei of a radioactive atom undergoing decay is called radioactivity. Example of radioactive material is uranium, thorium etc.
Question: 10
A radioactive substance is oxidized. What changes would you expect to take place in the nature of radioactivity? Explain your answer.
Solution: As the radioactivity is a nuclear phenomenon the oxidization will not affect the radioactivity.
Question: 11
A radioactive source emits three types of radiations.
(a.) Name the three radiations.
(b.) Name the radiations which are deflected by the electric field.
(c.) Name the radiation which is most penetrating.
(d.) Name the radiation which travels with the speed of light.
(e.) Name the radiation which has the highest ionizing power.
(f). Name the radiation consisting of the same kind of particles as the cathode rays.
Solution:
(a.) Three types of radiation are alpha beta and gamma.
(b.) Alpha and beta radiations.
(c.) Gamma radiations.
(d.) Gamma radiations.
(e.) Alpha radiations.
(f.) Beta radiations.
Question: 12
A radioactive source emits three types of radiations.
(a.) Name the radiation of zero mass.
(b.) Name the radiation which has the lowest ionising 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, it is found to be the atom of model of its neutral atom.
(f.) From which part of the atom do these radiations come?
Solution:
a.) Gamma radiations.
b.) Gamma radiations.
c.) Alpha radiations.
d.) Alpha particle has positive charge equal to 3.2 x 10-19C and mass is 6.68 x 10-27 kg.
e.) Alpha particle becomes neutral it is found to be model of helium atom.
f.) Radiations comes from nucleus of atom.
Question: 13
The diagram in the figure shows a radioactive source S placed in a thick lead walled container. The radiations given out 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).
Solution:
a.) Radiations labelled as A, B and are gamma, beta and alpha respectively.
b.) As the particles are moving through a magnetic field alpha particle will get deflected more as it has +2 charge and C is deflected the highest. There is no deflection in A hence that is gamma radiation and B is slightly deflected that is a property of beta particle having charge -1.
Question: 14
Fig. 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)
Solution:
a.)
b.) Fleming’s left hand rule.
Question: 15
Fig. 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 deflected the most? Give reason.
(e.) Which among the three radiations causes the least biological damage?
Solution:
a.)
b.) The source is kept in the lead container with narrow opening to make sure radiations does not spread in the environment as they are hazardous.
c.) Gamma radiations.
d.) Beta particles. As beta particles are charged and are very light they get deflected the most.
e.) Alpha particles.
Question: 16
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.
Solution: The nature of particles plays very important role in their deflection produced in the magnetic field. The alpha and beta being charged particles gets deflected in a magnetic field on the other hand the gamma particle is neutral hence it does not show any deflection.
Question: 17
Is it possible to deflect γ radiations in a way similar to α and β particles, using the electric or magnetic field? Give reasons.
Solution: no. As the gamma radiations are neutral it is not possible to deflect γ radiations in a way similar to α and β particles, using the electric or magnetic field.
Question: 18
State following four properties each of α, β and γ radiations: (a) nature, (b) charge, (c) mass, and (d) effect of the electric field.
Solution:
| Property | Alpha | Beta | Gamma |
| Nature | Positive particles | Negative particles | Electromagnetic radiations |
| Charge | Positive charge | Negative charge | Neutral |
| Mass | Equal to mass of helium nucleus | Equal to the mass of electron | No mass |
| Effect of the electric field | Less deflected | More deflected but opposite to alpha particles. | No deviation. |
Question: 19
Arrange the α, β and γ radiations in ascending order of their (i) ionizing power, and (ii) penetrating power.
Solution:
i.) Ionizing power – α, β and γ is the ascending order.
ii.) Penetrating power – γ, β and α is the ascending order.
Question: 20
State the speed of each of α, β and γ radiations.
Solution: speed of alpha radiation is 107 m/s. The speed of beta radiation is 2.7 x 108 m/s. The speed of gamma radiation is 3 x 108 m/s.
Question: 21
(a) What is the composition of α, β and γ radiations?
(b) Which one α, β and γ radiation has the least penetrating power?
Solution:
a.) Alpha radiations are made up of two protons and two neutrons. The beta particle is made up of one electron and gamma is electromagnetic radiation.
b.) Alpha being the bulkiest particle it has least penetrating power.
Question: 22
How are γ radiations produced? Mention two common properties of the gamma radiations and visible light.
Solution: The nucleus releases extra energy during excitation in the form of gamma rays. Visible light and gamma rays remain unaffected to any electric or magnetic field and have same speed.
Question: 23
An α particle captures (i) one electron, (ii) two electrons. In each case, what does it change to?
Solution:
If alpha particle catches one electron it becomes positively charged helium ion. When alpha particle catches two electrons it becomes helium atom.
Question: 24
‘Radioactivity is a nuclear phenomenon’. Comment on this statement.
Solution: Radioactivity of an atom is unaffected to any change in the physical or chemical change in atom such as temperature, pressure or oxidation state. Hence, it is clear that radio activity is a nuclear phenomenon.
Question: 25
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?
Solution: When a beta particle is released the number of nuclear particles remains the same but the number of protons increased and there is decrease in the number of neutrons.
APZ ————–> APZ+1 0e-1
Parent nucleus daughter nucleus + beta particle
The atomic number of the atom is not conserved it increases.
The mass number is conserved.
Question: 26
A certain radioactive nucleus emits a particle that leaves its mass number unchanged, but increases its atomic number by one. Identify the particle and write its symbol.
Solution: If the radioactive nucleus emits a particle that leaves its mass number unchanged, but increases its atomic number by one then the particle is beta
Symbol of beta particle is 0e-1
Question: 27
What happens to the (i) atomic number, (ii) mass number of the nucleus of an element when (a) an α particle, (b) a β particle, and (c) γ radiation, is emitted?
Solution:
a.) When alpha particle is emitted atomic number decreases by 2 and mass number decreases by 4
b.) When beta particle is remitted atomic number increases by 1 and mass number remains unchanged.
c.) When gamma radiations are emitted their no change in atomic number as well as mass number.
Question: 28
What happens to the position of an element in the periodic table when its nucleus emits (a) an α particle, (b) a β particle and (c) γ radiation? Give a reason for your answer.
Solution:
a.) When alpha particle is emitted daughter element moves to two places left to parent element in the periodic table. Because as the alpha particle is emitted the atomic number decreases by 2.
b.) When beta particle is remitted the new element moves 1 place right to parent element in the periodic table. As the beta particle is emitted the atomic number increases by 1.
c.) When gamma radiations are emitted their no change position of atom.
Question: 29
What changes occur in a nucleus of a radioactive element when it emits (a) an alpha particle, (b) a beta particle, (c) gamma radiation? Give one example, in each case (a) and (b) in support of your answer.
Solution:
a.) When alpha particle is emitted atomic number decreases by 2 and mass number decreases by 4.
For example,
238U92 ———-> 234Th90 + 4He2
Parent nucleus daughter nucleus alpha particle
b.) When beta particle is remitted atomic number increases by 1 and mass number remains unchanged.
For example,
1n0 —————-> 1P1 + 0e-1
Parent nucleus daughter nucleus beta particle
c.) When gamma radiations are emitted their no change in atomic number as well as mass number.
APZ —————> *APZ + γ
Parent nucleus daughter nucleus gamma radiations
Question: 30
(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 the nucleus A?
(d) Does the composition of nucleus C change if it emits the γ radiation?
Solution:
a.) The composition of B is 82 protons and 126 neutrons.
b.) The composition of C is 83 protons and 125 neutrons.
c.) Mass number of nucleus A is 212.
d.) Composition of C does not change if it emits gamma radiation.
Question: 31
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 emission of a particle.
(a.) Name the particle emitted.
(b.) Explain how you arrived at your answer.
(c.) State the change in the form of a reaction.
Solution:
a.) Particle emitted is alpha.
b.) As the atomic number of parent nucleus decreases by 2 and mass number decreases by 4 which indicates that the particle emitted is alpha particle.
c.) Reaction
238P92 ————> 234Q90 + 4He2
Parent nucleus daughter nucleus alpha particle
Question: 32
State whether the following nuclear disintegrations are allowed or not (star indicates an excited state). Give reason if it is not allowed.
Solutions:
a.) This transition is allowed. The parent atom is in excited state and then it emits a gamma radiation to come to ground state. There is no change in atomic number or mass number
b.) This transition is not allowed as the daughter nucleus has not undergone any mass change. For a nucleus to emit a alpha particle it necessary that its mass number decreases by 4.
Question: 33
A nucleus 24Na11 is Beta-radioactive.
(a.) What are the numbers 24 and 11 called ?
(b.) Write the equation representing B-decay.
(c.) What general name is given to the product nucleus with respect to 24Na11 ?
Solutions:
a.) 24 is the mass number and 11 is atomic number.
b.) Equation
24Na11 ———-> 24Mg12 + 0e-1
C.) Product 24Mg12 is an isobar of 24Na11.
Question: 34
A nucleus of stable phosphorus has 15 protons and 16 neutrons.
(a.) What is its atomic number and mass number?
(b.) The nucleus of radio phosphorus has one neutron more than the stable nucleus. What will be its atomic number and mass number?
(c.) What will be the atomic number and mass number of new nucleus formed by the decay of a B-particle by the radio phosphorus in part (b)?
Solutions:
a.) Atomic number of phosphorus is 15 and atomic mass number is 15+16 = 31
b.) As neutron is extra there will be no change in atomic number it remains same 15 and mass number is increased by 1 hence it becomes 32.
c.) Beta particle emission increases the atomic number by 1 and does not affect mass number. So, atomic number gets increased by 1 and becomes 16 and mass number remains the same as 32.
Question: 35
An element P disintegrates by alpha emission and thenew element suffers two further disintegrations, both by Beta emission, to form an element Q. Explain the fact that P and Q are isotopes.
Solutions:
When P disintegrates by Alpha emission the atomic number of P decreases by 2 and mass number decreases by 4.
APZ ——————–> A-4PZ-2 + 4He2
Further this daughter nucleus disintegrates twice to give 2 beta particles and forms Q.
A-4PZ- —————-> 2A-4QZ + 2 0e-1
As the atomic number of P and Q is same and they only differ in mass number it proves that P and Q are isotopes.
Question: 36
A nucleus AXZ emits 2 alpha particles and 1 beta particle to form a nucleus 222R85. Find the atomic number and mass number of X?
Solutions: Given
AXZ ————–> 222R85 + 2 4He2 + 0e-1
Therefore,
Atomic number Z = 85 + 4 – 1
Z = 88
Mass number A = 222 + 8
A = 230
Question: 37
Complete the following sentences:
(a.) The mass number and atomic number of an element are not changed when it emits………..
(b.) The atomic number of a radioactive element is not changed when it emits…………
(c.) During the emission of a beta particle, the …………. number remains same.
Solutions:
- Gamma radiations
- Gamma radiations
- Mass
Question: 39
What are radio isotopes? Give one example of a radio isotope. State one use of radio isotope.
Solutions: Radio isotopes are radioactive isotopes. For example, carbon has two isotopes C12 and C14 in which C14 is radioactive. Radio isotopes are used in medical field and research field.
Question: 40
Why alpha particles are not used in radio therapy?
Solutions: Alpha particles can no penetrate human skin hence they are not used for radio therapy.
Question: 41
Why do we usually use isotopes emitting gamma radiations as radioactive tracers in medical science.
Solutions: Gamma radiations are highly penetrative. As they are neutral they tend to show no ionizing capability which can be harmful for human body. Hence, gamma radiations are used as medical tracers.
Question: 42
When does the nucleus of an atom tend to become radioactive?
Solutions: When the repulsion between internuclear particles increases the nuclear force also increases. Hence that nucleus becomes radioactive to get stabilized.
Question: 43
Which of the following is the radio isotope in the following pair
- 12C6, 14C6
- 30P15, 32P15
- 39K19, 40K19
Solutions:
- 14C6
- 32P15
- 40K19
The number neutrons of above isotopes are more than the required quantity.Hence, these isotopes are radioactive.
Question: 44
State the medical use of radioactivity.
Solutions: Radioactivity is used to cure many diseases such as cancer, leukemia etc. The radiations from cobalt 60 are used to kill cancerous cells in the malignant tumour. The salts od weak radioactive source such as sodium chloride are used for diagnostic purpose. Such radio isotopes are called as tracers.
Gamma rays are used for sterilization of the equipment which is way cheaper than using heat.
Question: 45
Arrange the alpha, beta and gamma radiations in ascending order of their biological damage.
Solutions: alpha < beta < gamma
Based on the penetrating power gamma radiations damage the most and alpha particles damage the least.
Question: 46
Name two main sources of nuclear radiations. How are the nuclear radiations harmful?
Solutions: Two main sources of nuclear radiations are nuclear fall out from an nuclear plant and nuclear waste.
Nuclear radiations are harmful as the radiations can kill the cells in human body, can cause unwanted mutations or can cause radioactive burns.
Question: 47
State two safety measures to be taken while establishing a nuclear power plant.
Solutions: (1) Ensure that the people working in nuclear plant are not exposed to nuclear radiation
(2) the nuclear reactor must be housed in an airtight building of strong concrete structure which can withstand fire, earthquake, and explosions.
Question: 48
What is meant by nuclear waste? State one way for safe disposal of nuclear waste.
Solutions: The radioactive material let after its use is called nuclear waste.
Nuclear waste must be kept in thick casks and then they must buried in specially constructed deep underground stores.
Question: 49
State three safety precautions that you would take while handling radioactive substances.
Solutions: (a) I must wear special lead lined aprons and lead gloves.
(b) Must handle the radioactive material with long lead thongs.
(c) Must know all the information about the material we are working with most importantly safety limit.
Question: 50
Why should a radioactive substance not be touched by hand?
Solution: Nuclear radiations are harmful as the radiations can kill the cells in human body, can cause unwanted mutations or can cause radioactive burns. Hence, a radioactive substance should not be touched by hand.
Question: 51
What do you mean by background radiations? Name its two sources. Is it possible for us to keep ourselves away from it?
Solutions: Background radiations are the radiation to be which we all are exposed, even in absence of a visible radioactive source.
The two types of background radiation sources are internal source such as radioactive material present in our body and outer source such as cosmic rays, naturally occurring radioactive substances.
No, it is not possible for us to keep ourselves away from it.
MULTIPLE CHOICE TYPE
Question: 1
A radioactive substance emits radiations:
(a) α, β and γ simultaneously
(b) in the order α, β and γ one by one
(c) X-rays and γ-rays
(d) α or β.
Solution:(a) α, β and γ simultaneously
Question: 2
In β-emission from a radioactive substance, an electron is ejected. This electron comes from:
(a) the outermost orbit of atom
(b) the inner orbits of atom
(c) the surface of substance
(d) the nucleus of atom
Solution:(d) the nucleus of atom
Question: 3
The least penetrating radiation is:
(a) α-particles
(b) β-particles
(c) X-rays
(d) γ-radiations
Solution: (a) α-particles
Question: 4
The radiation suffering the maximum deflection in a magnetic field is:
(a) α-particles
(b) β-particles
(c) X-rays
(d) γ-radiations
Solution: (b) β-particles.
Exercise 12 (B)
Question: 1
What do you mean by nuclear energy? What is responsible for its release?
Solution: The energy released by a nucleus during the nuclear reaction such as fission of fusion of nucleus is called as nuclear energy. Nuclear reactions are responsible for its release
Question: 2
Write down the Einstein’s mass-energy equivalence relation, explaining the meaning of each symbol used in it.
Solution:
Einstein’s mass-energy equivalence is E = ∆m x c2
Where,
∆m = loss of mass in kg
c = speed of light = 3 x 108 m/s
and E is energy in joule.
Question: 3
(a) What is a.m.u? Express 1 a.m.u. in MeV.
(b) Write the approximate mass of a proton, neutron and electron in a.m.u.
Solution:
a.) Mass of atomic particle is expressed in atomic mass unit i.e.a.m.u.
1 a.m.u. = 931 MeV
b.) Mass of proton = 1.00727 a.m.u.
Mass of neutron = 1.00865 a.m.u.
Mass of electron = 0.00055 a.m..u.
Question: 4
What is nuclear fission? Name the particle used for it. Write one fission reaction.
Solution: Nuclear fission is the reaction in which a parent nucleus splits into two daughter nuclei of nearly same size. To carry out this fission the nucleus is bombarded with slow neutrons.
For example,
Question: 5
(a.) Name two isotopes of uranium which are fissionable.
(b.) Which of the isotope mentioned in part (a) above is easily fissionable? Give reason.
(c.) State whether the neutron needed for fission reaction of the isotope mentioned in part (b) above, is slow or fast?
Solution:
a.) Fissionable isotopes of uranium are238U92 and 235U92
b.) 235U92 is easily fissionable than 238U92
c.) The fission of 235U92 can be done by both slow and fast neutrons.
Question: 6
Write the approximate value of the energy released in the fission of one nucleus of 
. What is the reason for it?
Solution:
The energy released in fission of one 235U92 is about 190 MeV. According Einstein’s mass energy equivalence the energy released is mostly due to mass loss in the mass which is difference between sum of mass of parent nucleus and sum of masses of daughter nuclei.
Question: 7
Complete the following nuclear fission reactions:
Question: 8
What do you mean by the chain reaction in nuclear fission? How is it controlled?
Solution: When a nuclear fission reaction takes place more neutrons are released which can be further used for more nuclear fission. Vast amount of energy is released in this reaction. This reaction can be controlled using neutron absorbers such as cadmium rods which absorbs excessive neutrons.
Question: 9
State two uses of nuclear fission?
Solution: Nuclear fission reaction can be used in nuclear bomb with fast and uncontrolled reaction. Nuclear fission reaction can be used in nuclear reactors in slow and controlled manner.
Question: 10
Give two differences between the radioactive decay and nuclear fission.
Solution:
| Radioactive decay |
Nuclear fission |
| It is a spontaneous process. | It can not occur by itself. It can be initiated when neutrons bombarded on heavy nucleus. |
| Rate of this reaction can not be controlled. | Rate of this reaction can be controlled. |
Question: 11
(a.) What is nuclear fusion? Give one example and write its nuclear reaction.
(b.) What other name is given to nuclear fusion? Give reason.
Solution:
a.) Nuclear fusion reaction is the reaction where two lighter nuclei fuse together to form a heavy nucleus which releases enormous amount of energy.
1H1 + 1H1 ————> 2H1 + 1n0 + 0.42MeV
b.) Nuclear fusion reactions takes place at very high temperature hence called thermonuclear reaction.
Question: 12
Why is a very high temperature required for the process of nuclear fusion? State the approximate temperature required.
Solution: The nuclear fusion reaction is a reaction between two positively charged entities hence the force of repulsion is great. This fusion can not happen at normal temperature. To overcome this repulsion temperature must be very high for nuclear fusion reaction to happen.
The approximate temperature required for fusion is about 107 K. at this temperature nuclei gains enough kinetic energy to overcome the repulsion.
Question: 13
(a.) Write one nuclear fusion reaction.
(b.) State the approximate value of energy released in the reaction mentioned in part
(c.) Give reason for the release of energy stated in part (b).
Solution:
a.) 1H1 + 1H1 ————> 2H1 + 1n0 + 0.42MeV
b.) The energy released in part (a) is 0.42 MeV.
c.) Energy released in an nuclear fusion is loss in total mass as the mass of heavy nucleus is less than sum of the mass of two lighter nuclei fusing.
Question: 14
Complete the following fusion reactions:
Question: 15
(a.) Name the process, nuclear fission or nuclear fusion, in which the energy released per unit mass is more?
(b.) Name the process, fission or fusion which is possible at ordinary temperature.
Solution:
- Nuclear fusion is the reaction in which the energy is released per unit mass is more.
- Nuclear fission is possible at ordinary temperature.
Question: 16
(a) State one similarity in the process of nuclear fission and fusion.
(b) State two differences between the process of nuclear fission and fusion.
Solution:
a.) High amount of energy is released in both reaction fusion as well as fission.
b.)
| Nuclear fusion | Nuclear fission |
| Two lighter nuclei combine to form a heavy nucleus. | A heavy nucleus split into two lighter nuclei. |
| This reaction requires very high temperature to start. | This reaction can occur at normal temperature. |
Question: 17
Give two examples of nuclear fusion.
Solution:
a.) 3He2 + 2H1 ————–> 4He2+ 1H1 + energy
b.) 2H1 + 2H1 —————-> 4He2+ 1n0 + energy
Question: 18
What is the source of energy of sun or stars?
Solution: The source of energy of sun or stars is nuclear fusion reactions. As the temperature of these stars is high, lighter nuclei likes of hydrogen combine to form helium which releases tremendous amount of energy.
Question: 19
Name the following nuclear reactions:
Solution:
a.) This reaction is nuclear fission.
b.) This reaction is nuclear fusion.
MULTIPLE CHOICE TYPE
Question: 1
The particle used in nuclear fission for bombardment is:
(a) alpha particle
(b) proton
(c) beta particle
(d) neutron.
Solution:(d) neutron.
The particle used in nuclear fission for bombardment is neutron
Question: 2
The temperature required for the process of nuclear fusion is nearly:
(a) 1000 K
(b) 104 K
(c) 105 K
(d) 107 K
Solution:(d) 107 K
The temperature required for the process of nuclear fusion is nearly 107 K
NUMERICAL
Question: 1
In fission of one uranium-235 nucleus, the loss in mass is 0.2 a.m.u. Calculate the energy released.
Solution: 1 a.m.u. = 931 MeV
Loss of mass = 0.2 a.m.u.
Energy released is equal to loss of mass = 0.2 x 931
Energy released = 186.2 MeV.
Question: 2
When four hydrogen nuclei combine to form a helium nucleus in the interior of the sun, the loss in mass is 0.0265 a.m.u. How much energy is released?
Solution: 1 a.m.u. = 931 MeV
Loss of mass = 0.0265 a.m.u.
Energy released is equal to loss of mass = 0.0265 x 931
Energy released = 24.7 MeV.
