when an atomic nucleus emits a beta particle what happens to the atomic number of the atom

ICSE Solutions forChapter 12 Radioactive decay Course ten Selina Physics

Exercise 12 A

Question 1: What exercise you understand by the term radioactivity?

Reply ane: The process of self, spontaneous and random emission of a or P and y radiations from the nucleus of elements of atomic number higher than 82, is called radioactive decay.

Question two: What are radioactive substances? Give two examples of such substances.

Reply two: Radioactive substances are those which have the property of self emission of α or β and γ radiations.
Examples: Uranium, Thorium.

Question 3: Name the different radiations which are emitted by the radioactive substances.
Are all the radiations mentioned past you, emitted in a single radioactive disuse?

Answer 3: Post-obit three radiations are emitted by the radioactive substances:
(i) Alpha (α), (ii) Beta (β), and (3) Gamma (γ).
All the above radiations are not emitted in a single radioactive decay. At that place volition be either an α emission or a β emission, which may be accompained past γ-emission.

Question iv: Are all the radiation viz. α, β and γ emitted in a single radioactive decay?

Answer 4: All the above radiations are non emitted in a single disuse. In that location will exist either an α emission or a β emission, which may be accompanied by γ-emission.

Question v: Compare the penetrating powers of α, β and γ-radiation.

Answer five: γ -radiations are most 100 times more penetrating than β-radiation and 10,000 times more than penetrating than α-radiation.

Question half-dozen: Compare the ionising powers of α, β and γ  radiations.

Answer half dozen: The ionising ability of α-radiation is most 100 times that of β radiations and near 10,000 times that of γ-radiations.

Question 7: State the kind of nuclear reaction taking identify in a nucleus during the emission of a β-particle.

Respond 7: In the procedure of emission of a β-particle from the nucleus, a neutron changes into a proton past emitting a β-particle (electron).

Hence in the nucleus, the number of neutrons decreases by 1 with the emission of a β-particle and the number of protons increases by i. And then the sum of protons and neutrons, i.e., atomic mass remains the aforementioned only the atomic number increases by one.

Question 8: A certain nucleus has a mass number twenty and atomic number 9. Find the number of neutrons and protons present in it.

Answer 8: (i) Number of neutrons = Mass number – Diminutive number
= xx – 9 = 11
(ii) Number of protons = Atomic number = ix.

Question ix: Justify with reasons, whether the post-obit nuclear reactions are allowed or not.

Reply 9: (i) This reaction is immune because, the mass number as well as diminutive number are conserved here.
(ii) This reaction is not allowed because fifty-fifty though charge (atomic number) is conserved in it, the mass number [= A on the Fifty H.Due south. and equal to (A + iv)] on the R.H.South. is not conserved.

Question 10: An electrons emitter must have how much work function and melting point.

Answer x: An electron emitter must have low work function and loftier melting indicate.

Question xi: A radioactive nucleus undergoes a series of decays according to the sequence

If the mass number and atomic number of 10 ₃  are 172 and 69 respectively, what is the mass number and atomic number of X?

Answer 11: Mass no. of X = 180
Atomic no. of X = 72

Question 12: A mixture of radioactive substances gives off three types of radiations:
(i) Name the radiation which travels with the speed of light.
(ii) Name the radiation which has the highest ionizing ability.

Answer 12: (i) γ-rays.
(two) α-particles.

Question 13: Complete the following nuclear changes:


Answer 13:


Question xiv: An imaginary radioactive element ₉₂X²³⁵ decays to form X₁, X₂, X₃, 10_four, X₅ and Ten_{half dozen} nuclides, by ejecting two β-particles, followed by α-particles and again two β-particles, followed by α-particle. Represent the various nuclear change in the form of equation. Land the mass number and diminutive number of X₆. List the isotopes and isobars in the above nuclear equation.

Answer 14:

The mass number and diminutive number of X6 is 227 and 92 respectively.

Isotopes: (a) ₉₂Ten²³⁴, ₉₂X_iii ²³¹, ₉₂X_vi ²²⁷ (b) ₉₃10₁ ²³⁵, ₉₃X₄ ²³¹ (c) ₉₄Ten_ii ²³⁵, ₉₄X_five ²³¹

Isobars: (a) ₉₂X²³⁵, ₉₃10₁ ²³⁵, ₉₄X₂ ²³⁵ (b) ₉₂X_three ²³¹, ₉₃Ten_iv ²³¹, ₉₄X₅ ²³¹

Question fifteen: State two factors on which the rate of emission of thermions depends.

Answer 15: Charge per unit of emission of thermions depends on:
(i) The material of the surface
(ii) The temperature of the surface.

Question 16: The isotope of ₉₂U²³⁵ decays past alpha emission to an isotope of Thorium (Th). The Thorium isotope decays by beta emission to an isotope of Protactinium (Pa). Write down the equations to represent these ii nuclear changes.

Answer 16:


Question 17: A mixture of radioactive substances gives off three types of radiations.
(i) Name the radiation which are charged.
(ii) Name the radiation like in nature to cathode rays.
(iii) Name the radiation similar in nature to X-rays.
(4) Name the radiation which is deviated most in a magnetic field.
(five) Proper noun the radiations which is not affected by an electrical field.
(six) Proper name the radiations which has the maximum penetrating ability.
(vii) Name the radiation which has the highest ionising power.
(8) Name the radiation which has the highest speed.
(9) Name the radiation which when becomes neutral, become the atom of a rare gas.

Reply 17: (i) Blastoff and beta radiation are charged.
(ii) Beta radiation is similar in nature to cathode rays.
(iii) Gamma radiation is similar in nature to X-rays.
(4) Beta radiation deviates most in a magnetic field.
(v) Gamma radiation is not affected past an electric field.
(half-dozen) Gamma radiation has the maximum penetrating power.
(vii) Alpha radiation has the highest ionising power.
(viii) Gamma radiation has the highest speed.
(ix) Alpha radiation when become neutral become the atom of rare (helium) gas.

Question 18: Land, giving reasons, whether the following nuclear decays are immune or non?

Reply xviii: (i) This nuclear decay is allowed since the diminutive number and mass number are conserved.

(ii) This nuclear disuse is non allowed since the mass number is not conserved.
(iii) This nuclear disuse is not allowed since the atomic number and mass number both are non conserved.

Question 19: The nucleus ₈₄X²⁰² emits an alpha particle and forms the nucleus Y. Represent this change in the grade of an equation.

Answer nineteen:

Question 20: What changes will take place in the mass number and diminutive number of the nucleus Y if information technology emits gamma radiations?

Respond 20: No change in mass number and diminutive number when γ radiations are emitted out.

Question 21: How does the position of an chemical element alter in the periodic table when it emits out an blastoff particle?

Answer 21: When an element emits out an alpha particle, a new chemical element is formed with properties like to those of an element two places earlier in the periodic tabular array.

Question 22: What changes occur in the nucleus of a radioactive element when it emits an alpha particle? Show by an instance?

Answer 22:


Question 23: What will an alpha particle change into when it absorbs:
(i) One electron; (2) Two electrons?

Reply 23: (i) Unmarried ionised Helium (He ⁺ ), (ii) Helium atom.

Question 24: Land three properties of α-rays.

Respond 24: (i) Alpha rays are composed of helium nuclei.
(ii) Alpha rays ionise the gas through which they pass.
(three) Alpha rays are deflected by the electric and magnetic fields.

Question 25: What is the effect on the atomic mass and the atomic number of a radioactive element, afterwards the emission of an α-particle?

Answer 25: During the emission of an α-particle from the nucleus of a radioactive element, its atomic mass decreases by 4 and the diminutive number also decreases by 2. If_ZX^A represents a radioactive chemical element having atomic mass A and atomic number Z, so:


Question 26: When an alpha particle gains ii electrons it becomes neutral and becomes an atom of an element which is a rare gas. What is the proper name of this rare gas?

Respond 26: Helium gas.

Question 27: An atomic nucleus A is composed of 84 protons and 128 neutrons. It emits an α-particle and is transformed into nucleus B. Write down the composition of B.

Answer 27: A emits an α-particle, so in the nucleus of B, neutrons volition be 128 – ii = 126 and protons will be 84 – 2 = 82.

Question 28: State accuse and mass of (i) α-particle, (2) β-particle.

Answer 28: (i) The accuse on α-particle is iii.2 ×10 ^-19  coulomb and its mass is vi.67 × 10 ^-27  kg (i.e., well-nigh four times the mass of proton).
(ii) The accuse on β-particle is – one.6 × 10 ^-xix  coulomb and its mass is nine.1 × ten ^-31  kg.

Question 29: How does the position of an chemical element change in the periodic tabular array when it emits out a beta particle?

Reply 29: When an element emits out a beta particle, a new element is formed with properties similar to those of an element ane place afterwards in the periodic table.

Question 30: What are α-and β-radiations?

Answer 30: α radiations are positively charged particles with charge + 2e and mass 4m _p  where e is electronic accuse (i.eastward., charge on a proton) and one thousand _p  is the mass of a proton.
β radiation are negatively charged particles (i.e., electrons) with charge – e and mass 1/1836 times the mass of a proton.
γ-radiation are electromagnetic waves of wavelength in the range 0.001 Å.

Question 31: State three common properties of beta rays and cathode rays.

Reply 31: (i) Beta rays and cathode rays both are composed of electrons.
(ii) Beta rays and cathode rays both are deflected by the electric and magnetic fields in the aforementioned direction.
(iii) Beta rays and cathode rays both ionise the gas through which they laissez passer.

Question 32: The nucleus of an atom does not contain electrons. Explain how is it possible for the nucleus to emit a beta particle which is fast moving electron.

Answer 32: The nucleus emits a beta particle when a neutron inside it changes into a proton. The reaction is


Question 33: What happens to the diminutive number of an chemical element when it emits:
(i) An blastoff particle; (ii) A beta particle.

Respond 33:


Question 34: A radioactive carbon nucleus _half-dozenC^fourteen  emits a β-particle to form a nitrogen nucleus. Stand for the change past an equation showing the atomic and mass number of each elements.

Reply 34: When the nucleus of an element emits a beta particle, the number of protons increases by 1 and number of neutrons decreases by 1.


Question 35: Ii radioactive nuclei are represented past ₁₀A^p  and _yA^q and when p and q are mass numbers and x, y are the atomic number. How can the products be represented, i .east., what are the new values of p, q. ten and y subsequently the emission of an α-particle and a β-particle from A and B respectively.

Reply 35:

Question 36: A nucleus of an element has the symbol ₈₄P²⁰² , and emits an α-particle and then a β-particle. The final nucleus is _bQ^a  Detect a and b.

Answer 36:


Question 37: The nucleus B emit a β-particle and is transformed into nucleus C. What is the composition of C?

Reply 37:With the emission of a β-particle from nucleus B, number of protons volition increase by one, i.e., number of protons = 82 + 1 = 83 and number of neutrons volition be 126 – ane = 125, i.due east., the nucleus C will take 83 protons and 125 neutrons.
Mass number of nucleus A = Number of protons + number of neutrons
= 84 + 128 = 212.

Question 38: Explicate briefly what changes take place inside the nuclei when beta particles are emitted by a radioactive substance.

Reply 38: The mass number remains unchanged but the atomic number increases by one of the nuclei undergoing such a change.

Question 39: Which office of the atom undergoes a change in the process of radioactive decay?

Respond 39: The nucleus of the cantlet undergoes a alter in the process of radioactive decay.

Question xl: How practice infrared and γ-rays differ in (i) wavelength, (ii) penetrating power?

Respond twoscore: (i) Infrared rays are of much longer wavelength than that of γ rays. The wavelength of infrared rays lies between 8000 Å to 107 Å while that of γ rays lies between 0.001 Å to 0.1 Å.
(ii) γ rays are most penetrating while infrared rays nearly accept a negligible penetrating power.

Question 41: From α, β and γ-rays, name the i which travels with the speed of calorie-free?

Answer 41: γ-rays travel with the speed of light.

Question 42: From α, β and γ-rays, name the one which is not affected by an electric or magnetic field?

Respond 42: γ-rays are not affected by electric or magnetic field.

Question 43: Adapt α, β and γ-rays in ascending guild with respect to their (i) Penetrating ability,
(2) Ionizing power and (iii) Biological effect.

Reply 43: Given below:

Question 44: What changes occur in the nucleus of radioactive chemical element when it emits gamma radiations? Give an example.

Answer 44: When the nucleus of a radioactive element emits gamma radiation, there is no change inside the nucleus except that its excess free energy is released in the form of y-radiations.

The star indicates the excited state of nucleus.

Question 45: What is the value of the speed of gamma radiations in air or vacuum?

Reply 45: Speed of γ radiation = 3×x ^viii  m/s in air or vacuum.

Question 46: What are beta rays and gamma rays?

Answer 46: β-rays are a stream of electrons emitted by the nucleus of an cantlet and γ-rays are electromagnetic waves of high frequency given off past nuclei.

Question 47: Name the radioactive radiations which have the least penetrating ability.

Answer 47: a-radiations have the least penetrating power.

Question 48: Explicate why blastoff and beta-particles are deflected in an electric or a magnetic field merely gamma: rays are not deflected in such a field.

Answer 48: α and β are positive and negative charged particles respectively, therefore these are deflected in electrical or magnetic field whereas γ radiations are non charged particles so does non deflect.

Question 49: A radioactive substance, is oxidised. What change would yous expect to take place in the nature of radioactivity? Requite reason for your answer.

Answer 49: No changes equally the nucleus of the element is not involved.

Question 50: Land the medical use of radioactivity.

Reply 50: (i) Radioactive radiation (gamma rays) are used to cure diseases such equally cancer etc.
(2) Radioisotopes such as NaCl etc. are used for diagnosis.

Question 51: explain, why radium paint, consisting of zinc sulphide and a trace of radium salt, glows in the dark?

Answer 51: Radium is a radioactive substance. It gives out radioactive radiations which show fluorescence in zinc sulphide. Zinc sulphide is a fluorescent material, so it glows in dark.

Question 52: State one use of radio-isotopes.

Answer 52: The most important one utilise of radio-isotopes is in medicines which are used mainly to cure cancer.

Question 53: State three safe precautions that you would take while using a radioactive substance.

Answer 53: (i) We should put on special lead lined aprons, lead gloves and special film badges.
(two) We should non touch the radioactive substances only should handle them with long lead tongs.
(iii) The radioactive substance should be kept in a thick walled atomic number 82 container:

Question 54: It is advised non to touch a radioactive substance by hand. Give reason.

Answer 54: The reason is that the radiation (α, β and γ) emitted by a radioactive substance accept large penetrating power.

Question 55: Which of the radioactive radiations tin cause astringent genetical disorders and are deflected by an electric field?

Answer 55: γ-radiations can cause severe genetical disorder α and β are deflected by an electric field.

Question 56: Give whatsoever two important sources of background radiation.

Respond 56: Two sources of background radiations are:
(i) Potassium nowadays in our trunk.
(ii) Cosmic rays coming from outer space.

Question 57: What is mean by background radiation?

Answer 57: Background radiations are the radioactive radiations to which we all are exposed even in the absence of an actual visible radioactive source. It total does is not very large, then it does non cause whatever serious biological damage to u.s..

Question 58: What is nuclear energy? Name the process used for producing electricity using nuclear energy.

Answer 58: Nuclear energy is the energy released past the atom's nucleus during a nuclear reaction. It is an exothermic process. The procedure of Nuclear fission is used to produce electricity.

Question 59: Land one important advantage and disadvantage each of using nuclear energy for producing electricity.

Respond 59: Advantage:
Higher order of electric free energy can exist produced.
Disadvantage: Difficult to control the higher order free energy release as it damages the control rods and difficult to dispose the nuclear wastes.

Question 60: State the energy conversion taking place in a solar cell.

Answer lx: Energy conversion taking identify in solar cell is Solar energy to Electric energy.

Question 61: What is meant by nuclear waste?

Answer 61: After disintegration, the radioactive material finally converts into atomic number 82 and nevertheless information technology holds some radioactivity. This is called nuclear waste material.

Question 62: Propose one constructive manner for the prophylactic disposal of nuclear waste product.

Answer 62: Delay and decay method is the effective manner for the safe disposal of nuclear waste.

Question 63: Land iii ways of obtaining an electron-axle.

Answer 63: The three means are:
(i) In a cathode ray tube, when pressure of 0.01 mm of Hg and a high p.d. of nigh 10000 V is practical beyond its electrodes.
(ii) In a diode-valve, information technology is produced from the heated cathode from where they are attracted by the anode plate kept at a loftier positive potential.
(iii) Electrons are also produced in the process known as 'photo electric emission' by focussing low-cal on a metal surface coated with cesium oxide.

Question 64: State iii safety precautions that you would take while handling the radioactive substances.

Answer 64: (i) The people working with radioactive materials should use mechanical devices such as tongs, clamps, tweezers, etc., to help minimize exposure.
(2) The people working with radioactive materials should article of clothing special atomic number 82 lined lab coasts, gloves and safety spectacles and remove them when leaving the piece of work expanse or laboratory.
(three) All radioactive materials should be stored in specially designed thick atomic number 82 containers with a very narrow opening so as to stop radiation coming out from other directions.

Long Answers

Question 1: Name the particles that constitute the cathode rays. Country some properties of cathode rays.

Answer 1: Cathode rays are made up of electrons—the fundamental negatively charged particles. These rays have the following backdrop, among others.
(i) They can touch photographic plates and produce fluorescence in materials similar zinc sulphide.
(ii) They carry momentum and energy.
(iii) They are deflected by electric and magnetic field in the sense in which negatively charged particles are deflected.

Question 2: Mention four properties of Becquerel rays.

Respond 2: The four properties of Becqueral rays are:
(i) They take penetrating power.
(ii) They affect a photographic plate.
(iii) They can ionize a gas or air through which they pass.
(four) They are deflected by electric and magnetic fields.

Question 3: Proper noun the 3 main parts of a hot cathode ray tube. Mention one important role of ear primary parts:
State the principle on which the functioning of a nuclear reactor is based.

Answer 3: Three master parts of hot cathode ray tube:
(i) The electron gun,
(2) The deflecting arrangement,
(iii) The fluorescent screen.
Functions:
(i) Electron gun gives out fine beam of electrons.
(ii) The deflecting arrangement deflect electron beam in horizontal and vertical management.
(iii) The fluorescent screen gives bright spot on stirking of electron.

Question four: How many alpha and beta particles are emitted when the Uranium nucleus decays _nineP²³⁸  to Lead If ₈₄P²⁰⁶  ?

Answer 4: On emission of one alpha particle, the mass number decreases by 4. With the emission of an alpha particle, the atomic number decreases by 2 but when a β-particle is emitted, the diminutive number increases by 1.

No. of α-particles emitted = 8.
No. of β-particles emitted = 6.

Question 5: State three safety precautions that you would take while handling the radioactive substances.

Respond 5: (i) The people working with radioactive materials should utilize mechanical devices such as tongs, clamps, tweezers, etc., to aid minimize exposure.
(two) The people working with radioactive materials should wear special lead lined lab coasts, gloves and condom glasses and remove them when leaving the work area or laboratory.
(iii) All radioactive materials should be stored in specially designed thick lead containers with a very narrow opening so as to end radiations coming out from other directions.

Figure Based Curt Answers

Question 1: Draw a simplified labelled diagram of a hot cathode ray tube.

Reply 1:

Question 2: The figure (i) shows a radioactive source S placed in a thick walled lead container. The radiations given off laissez passer through a magnetic field interim in direction perpendicular to the plane of paper inwards every bit shown past X. Re-create the diagram and show the path of radiations. Explain why the source is kept in a thick-walled lead container.

Answer 2: The figure (ii) shows the path of radiation in the magnetic field. The source is kept in a thick-walled lead container so that the it.
Radiations may not come out in the undesired management otherwise they will harm the person working on.

Effigy Based Long Answers

Question 1: Answer the questions with respect to the post-obit diagram:

(i) Name the charged particles emitted from the heated filament? Name the phenomenon of emission of these particles.
(2) A axle of such particles, afterward acceleration, is allowed to strike a metal plate C. Radiation B is given off. Name the radiations B.
(iii) Proper noun the textile of target C.
(iv) Country two properties of radiation B dissimilar from those of visible lite.
(v) State 2 factors on which the wavelength of radiations B depends.
(six) Land two uses of radiations B.
(vii)Why is it necessary to absurd the tube?

Answer ane: (i) 'Electrons'. The phenomenon of emission of these particles is called "thermionic emission".
(ii) Radiations B is chosen "X-rays".
(iii) The material of the target C is "tungsten."
(iv) The properties of radiation B differ from those of visible lite are:
(a) These radiations can penetrate through the substances which are opaque to visible light.
(b) They destroy the living cells.
(v) The wavelength of radiation B depends upon:
(a) Potential difference applied between cathode and anode.
(b) Material of the target.
(vi) Uses:
(a) In the field of medical science (X-rays photography used in surgery)
(b) In scientific work (to study crystal construction).
(vii) A large amount of estrus is produced when the high kinetic energy electrons strike the target. Therefore it is necessary to absurd the tube.

Question 2: An element P disintegrates by beta-emission and the new chemical element suffers two farther disintegrations, both by beta-emission, to form an element Q. Evidence that P and Q are isotopes.

Solution 2:

The diminutive numbers (Z) of P and Q are the same simply their mass numbers [A and (A-4)] are dissimilar. And so P and Q are isotopes.

Question 3: An element X has the symbol ₈₄Ten²⁰²  . It emits an alpha-particle and and then a beta-particle. The final nucleus is _bY^a . Find a and b.

Solution 3:


Question 4: Consummate the post-obit fission reaction

Solution 4:

Long Numericals

Question 1: A certain nucleus X has a mass number 15 and atomic number 7. Find the number of neutrons. The nucleus 10 losses (i) one proton (2) one β-particle, (iii) one α-particle, Express each change and write the symbol of the new nucleus in each case.

Solution 1:

Question two: An element ₉₂U²³⁸ losses i alpha particle, and then one β-particle and then once more i β- particle to get the final nucleus _bQ^a  .
(i) Write down the values of a and b.
(ii) State the human relationship between the nuclei P and Q.

Solution ii:

Question 3: An isotope of uranium is ₉₂Y²³⁸  . , i.due east., it has mass number 235 and atomic number 92.
(i) Detect the number of electrons in the neutral atom of this isotope.
(2) Discover the number of protons and neutrons in its nucleus.
(three) Practice all isotopes have the aforementioned number of neutrons?
(4) What is the number of protons in ₉₂U²³⁸ ?
(v) Mention the relationship between ₉₂U²³⁵ and ₉₂U²³⁸ .

Solution 3:

(i) Since it is a neutral atom, the number of proton will be equal to the number of electrons.

Number of protons = Diminutive number = 92

∴ Number of electrons = 92

(ii) Atomic mass = Number of protons + Number of neutrons

Or, 235 = 92 + Number of neutrons

∴ Number of neutrons = 235 – 92 = 143

(iii) No. of isotopes of an element have the aforementioned atomic number simply they differ in their atomic masses, and hence in such isotopes, the number of neutron will be different.

(iv) In ₉₂U²³⁸, the diminutive number is 92 then the number of protons will as well exist 92.

(v) In ₉₂U²³⁸ and ₉₂U²³⁵, the difference is in their atomic masses but their atomic number is the same that is both have the same atomic number, 92. The element that differ in their atomic masses but have aforementioned diminutive number are called isotopes, hence ₉₂U²³⁸ and ₉₂U²³⁵ are the isotopes of the element uranium.

davisforritan69.blogspot.com

Source: https://www.icserankers.com/2020/11/icse-solutions-for-chapter12-radioactivity-class10-physics.html

Share this post