6.Radioactive

7/27/2019 6.Radioactive

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Name: ................................................................. Class:............................

Latih Tubi 7 : RADIOACTIVE

Perlis 20101.Diagram 2 shows the nuclear reaction involving the nucleus ofuranium-235 in a nuclear ractor

(a) Name the process as shown in the diagram 2

...................................................................................................................................... [1marks]

(b) The complete equations for the above reactions is given below

Find the value of x and y

(i) x :........... (ii) y :............... [2marks]

(c) name the energy produce and what couse the production of energy

........................................................................................................................................

.....................................................................................................................................[2marks]

Kedah20092. Diagram 6.1 shows the activity of a radioactive substance X and a radioactive substanceY being measured by a Geiger-Muller tube connected to a ratemeter.

Diagram 6.2 shows the decay curves obtained for radioactive substance X and radioactivesubstance Y.

QUEST. MARKS

1/05

2/08

3/12

4/205/20

6/20

TOTAL/85

/ X


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(a) What is the meaning of half life?

.....................[1 mark]

(b) Based on the decay curves in Diagram 6.2,(i) State the half life of radioactive substance X and radioactive substance Y.

X : ................................. Y : ................................. [2 marks]

(ii) For radioactive substance X and radioactive substance Y, what percentageremains undecayed after 10 minutes?

X : ................................. Y : ................................. [2 marks]

(c) Based on the answers to 6(b)(i) and 6(b)(ii), compare the decay rates of radioactivesubstance X and radioactive substance Y. Hence state the relationship between decay rate andhalf life.

...................................

...................[2 marks]

(d) Give a reason why the readings of the ratemeters did not drop to zero after radioactivesubstance X and radioactive substance Y were removed.

.....................[1 mark]

Pahang 20103. A technician is tracing water pipe line laid undergraund to detect leakeage point. Four types ofradioisotope are suggested to be used to detect the leaking point of the pipe. Small amaount ofradioisotope is dissolved in the water reservoir.

Radioisotpe Half-lifeTypes ofradiation

Physical state

Sodium-24 15 hours Gamma Liquid

Iodine-131 8 days Gamma Liquid

Radium-226 1600 year Alpha Solid

Phosphorus-32 15 days Beta SolidTable 8A Geiger-Muller tube counter is moved over the pipe according to layout plan. At a point, thecounter recorded a high radiation level indicating the point of leakage.


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(a) Based in table 8, state the most suitable properties of the radioisotope used to detect theleakage. Give reasons for the suitability of the properties.

(i) Half-life

............................................................................................................................... [1 mark]

Reason

............................................................................................................................... [1 mark]

(ii) Types of radiation

............................................................................................................................... [1 mark]

Reason

............................................................................................................................... [1 mark]

(iii) Physical state

............................................................................................................................... [1 mark]

Reason

............................................................................................................................... [1 mark]

(b) Radioisotope stratium-90 is of half-life 28 yearsFind the time for the activity to reduce to 1/8 of the original value

[2marks](c) State one advantages of radioisotope(1)

............................................................................................................................... [1 mark](d) A possible fusion reaction is shown by

H2

1+ H

3

1 He

4

2+ n

0

1+ energy

[ H2

1=2.014012u, H

3

1= 3.016029u, He

4

2= 4.002603u,

n0

1= 1.008665u, u = 1.66 x 10-27 kg]

(i) calculate the mass defect,m

[2marks]

(ii) calculate the energy,E released in the fusion reaction

[1marks]


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Negeri Sembilan 20094. Table 10.1 shows an equation of a reaction and total atomic mass before and after a nuclearfission.

Table 10.2 shows an equation of a reaction and total atomic mass before and after a nuclearfusion.

(a) (i) What is meant by a nuclear fission ? [1 mark](ii) Using only the information given in Table 10.1 and 10.2, compare nuclear fission andnuclear fusion. Hence state the relationship between mass and energy involved.

[5 marks]

(b) Nuclear fission produces a chain reaction. Describe how the chain reaction happens in anuclear fission of an atom of uranium. [4 marks]

(c) As a researcher , you are assigned to investigate the characteristics of a certain radioactiveisotope that could be used to detect the thickness of paper in a paper factory.Your answer should include the following aspects

(i) The state of matter of the radioactive isotope.(ii) The type of radiation emitted(iii) The half-life of the radioactive isotope(iv) The penetrating power of the radioactive isotope

(v) Suitable detectors of radioactive emissions [10 marks]

Melaka 20095. Radioactive material has some important uses in the field of agriculture such as to studythe effectiveness of fertilizers and control the population of pests.

(a) A researcher conducted an investigation using posphorus-32 to study theabsorption and movement of fertilizers in the plant. Diagram 12.1 shows howradioisotope posphorus-32 is injected to the stem of the plant. The half-life ofposphorus-32 is 14 days and emits -particles.


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Based on the information on radioactivity and Diagram 12.1 :(i) What is meant by half life? [1 marks]

(ii) What is -particles. [1 marks](iii) Name the most suitable detector could be used to detect -particles. [1 marks]

(b) The initial posphorus-32 activity is 800 counts per second. Calculate the time taken for thephosphorus-32 activity to decrease to 50 counts per second.

[2 marks]

(c) The population of pests can be controlled using radiation fromradioactive source. You are assigned to study the characteristics of some radioisotopes that aresuitable for use in controlling the population of pests. Table 12.2 shows the characteristics offour radioisotopes.

RadioisotopeCharacteristic of radioisotope

State of matter Type of ray Half-life

Iodine-131 Liquid Gamma 8 days

Xenon-133 Solid Beta 5 days

Cobalt-60 Solid Gamma 5 years

Strontium-90 Liquid Beta 8 years

Table 12.2

Explain the suitability of the characteristics of the radioisotope to be used in thecontrolling the population of pests based on the following aspects:

- State of matter- Types of ray- Half-life

Determine the most suitable radioisotope to be used and give the reason for yourchoice.

[8 marks](c) The following equation shows a fission reaction of Uranium-235.

(i) What is meant by a nuclear fission? [1mark](ii) Nuclear fission produces a chain reaction. Describe how the chain reaction occurs in a

nuclear fission of an atom of Uranium- 235.[4 marks]

(iii) The nuclear energy produced in the fission reaction of uranium-235 is 2.9 x 10-11 J. Calculate the total lost of mass in the reaction. [ c = 3.0 x 108 ms-1]

[2 marks]

Diagram 12.1


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Melaka 20106. Diagram 12.1 shows part of Uranium-238 radioactive decay series.

Diagram 12.1

(a) What is the meaning of radioactive decay? [1 marks]

(b) Based on Diagram 12.1;

(i) Uranium U238

92decays to Thorium Th

234

90.Write an equation to showthe decaying

process.[1marks]

(ii) Explain the changes in the nucleus of uranium-238 during the decaying process[2 marks]

(iii) Determine the number of alpha particles and beta particles produced by the radioactivedecaying series shown in Diagram 12.1.

[2 marks]

(iv) The half life of Pa234

91is 6.7 hours and initially has a mass 32 g. What is

the mass of Pa-234 after 33.5 hours?[2 marks]

(c) Diagram 12.2 shows a leakage of an underground water pipe line. Radioactive source isused to detect the spot of the water leakage.

(i) Explain how a radioactive source is used to detect the spot of the water leakage fromthe pipe.

[2 marks]

(ii) You are asked to investigate the characteristics of five radioactive sources shown inTable 12.Explain the suitability of each characteristic of the radioactive sources and determinethe most suitable radioactive source which can be used to locate the water leak.Give reasons for your choice.

[10 marks]

Table 12

Radioactivesource

Penetratingpower

EmittedRadiation

Half-life State ofmatter

P Low Alpha 16 hours Solid

Q Medium Beta 20 days Liquid

R Medium Beta 15 hours Liquid

S High Gamma 40 minutes SolidT High Gamma 10 hours Liquid


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SKEMA Latih Tubi 7 : RADIOACTIVE

Q Answer Marks

1(a) Nuclear fission 1

(b) X = 36Y = 92

11

(c) Heat energy/nuclear energyLoss of mass//mass defect

11

TOTAL 5

2(a) Time for the activity/mass/nucleus of the radioactive substance tobecome halfof the original activity

1

(b) (i) - X : 10 minutes- Y : 5 minutes

11

(ii) - X : 50 %- Y : 25 %

11

(c) - The decay rates for substance X is slower//vice versa- The shorter the half life, the higher the decay rate

11

(d) - Background radiation 1

Total: 8 marks

3(a)(i) Short Half LifeShort time taken to decay/Can decay faster and they leave harmless

daughter nuclei

11

(a)(ii) Gamma rayStrong penetration power/ Can penetrate the soil

11

(a)(iii) LiquidEasier to dissolve in water/ Produce more even radiations.

11

(b)T1/2 T1/2 T1/2t = n (T1/2)= 3 (28 years) = 84 years

11

(c) Thickness control/Examine contamination in canned food/Medical screening/treatment// smoke detector/ sterilizing/

1

(d)(i) Mass defect = (2.014012u + 3.016029u) (4.0022603u +1.008665u)= 0.018863 u = 0.018863 x 1.66 x 10-27 kg= 3.13 x 10-29 kg

11


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(d)(ii) E= mc2= 3.13 x 10-29 kgx(3.0 x 108 ms-1)2= 2.82 x 10-12 J

1

Total: 12marks

4(a)(i) Nuclear fission is the process of splitting a heavy nucleus into severalsmaller and lighter nuclei with release of energy

1

Nuclear f ission Nuclear fusionSplitting a heavy nucleus intolighter nucleus

Combining several light nuclei toform a heavy nucleus

There is a reduction of mass There is a reduction ofmass/mass defect

Energy is released Energy is released

Energy formed as a result of

defect/lost (E = mc2

)

Energy formed as a result of

defect/lost (E = mc2

)

2

1

1

1

(b) - neutron bombards a uranium-235 nucleus, splitting into two lighternuclei are produced.- the mass lost is converted into energy, according to Einsteins Principle

of Mass Energy Conservation, E = mc2

- the three neutrons will bombard other uranium nuclei continuously- cause the other remain nuclei to produce other 3 neutrons

1

1

11

characterist ics explanation

State of matter ; solid form easy to handle

beta-ray has high penetrating power/ ableto penetrate through the paper

the half-life is longer Can last longer/ can use forlonger period/ no need toreplace frequently

high penetratingpower/moderate

Can penetrate the paper

Use a Geiger Muller tube asdetector

Can detect beta rays/radioactive emission

2

2

2

2

2

Total: 20 marks

5(a) (i) The time taken for half of nucleus radioactive material todecay.

1

(ii) Fast moving electron / electron 1

(iii) Geiger-Muller tube 1

(b) 800 ---------> 400 ---------> 200 ----------> 100----------> 50 //14 days 14 days 14 days14 daysNo. of T 1/2 = 4- 4 x 14 days / 64 days

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(c) characterist ics explanation

The state of matter ofradioisotope is solid.

Easier to handled.

Emits gamma-ray. Penetrating power is high.

Long half-life. Last longer.

Cobalt-60. Because the state of matter is solid,

emits gamma-ray and long half-life

2222

(d) (i) The process of breaking up of on heavy nucleus into lighternucleus.

1


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(ii) - Neutron bombarded a uranium nucleus //Diagram- Three neutrons produced // Diagram- The new neutron bombarded a new uranium nucleus // Diagram- For every reaction, the neutrons produced will generate a chain reaction// Diagram

1111

(iii) E = mc22.9 x 10 -11 = m x (3.0 x 108)2

m = 3.22 x 10-28

kg

11

Total: 20marks

6(a) Radioactive decay is a process which unstable nucleus decay to become

stable nucleus by emittion radiation /photon

1

(b)(i) 1

(ii) 1st : During the alpha decay, the number of proton will decrease by 2/

proton number decrease by 2

2nd : and the number of neutron will also decrease by 2 / nucleon

decreases by 4

1

1

(iii) 1st : 4 alpha particles

2nd : 2 beta particles

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(iv) 1st : t = 33.5 /6.7 = 5 T1/2

2nd : 32 16 8 4 2 1 g

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(c)(i) 1st : put a radioactive substance into the water and let the waterflowto the location of the leak.2nd : The location of the leak has the highest / increase activity /reading on detector.

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(c)(ii) characterist ics explanation

has medium penetrating power can penetrate the soil and emerge

from the ground

B eta ray medium penetrating power /less

dangerous to the worker

Has a short half-life Short but enough time to detect

the radioactive /active in water

for ashort time so not harmful to the

water consumer

Liquid dissolved easily in water

Substance R short half-life, emits gamma ray ,

liquid and has high

penetrating power.

22222

Total: 20marks

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6.Radioactive