SPM 2003

Chapter Chap ter 5: Radioactiv Radioa ctivity ity

Mr. Kenneath Kenneat h Y.

SPM 2003 6. As a researcher, researcher, you are asked asked to investigate investigate the characteristics characteristics of a certain radioactive isotope that could be used to detect the thickness of paper in a paper paper factory. a !hat does does the ter" #isotop #isotope$ e$ "ean% "ean% &' "ark( b )he table belo* belo* sho*s the characteristic characteristic of five isotopes. +sotope

haracteristics of isotope State of -"itted alf/life "atter radiation Solid 1eta 2 years

Penetratin g po*er Mediu"

Strontiu"/ 0 obalt/60 Solid a""a 4 years igh 5enon/'33 as 1eta 4 days igh !ater i7u i7uiid 1eta 1eta '2 yea years Medi Mediu" u" containing /3 Poloniu"/ Soli Solid d Alph Alphaa '80 '80 days days o* o* 2'0 1ased on the table above, i. -9pl -9plai ain n the the suit suitab able le char charac acte teri rist stic icss of of iso isoto tope pess so so tha thatt it it can can be used to "easure "easure the thickness of paper in a paper paper industry. ii. ii. Sele Select ct the the "os "ostt suit suitab able le isot isotop opee to to be used used in in dete detect ctin ing g the the thickness of paper in the factory and give your reason. &'0 "arks(

Chapter 5: Radioactivity

Mr. Kenneath Y.

c Suggest briefly the arrange"ent of the paper thickness detector apparatus and state ho* radioactivity is used to detect the thickness of the paper. &3 "arks(

d Sketch a graph of activity against ti"e to illustrate ho* radioactive "aterials decay. :se your graph to e9plain ho* the half life is deter"ined. &8 "arks(

e )he half life of cobalt/60 is 4 years. alculate the ti"e taken for the activity of this isotope to decay to '2.4; of its initial value. &2 "arks( SPM 2008 <. Production of nuclear energy and detecting the volu"e the volu"e of a "aterial are t*o e9a"ples of the use of radioactive in industry. )able sho*s an e7uation of a reaction and total ato"ic "ass before and after a nuclear fusion. =uclear fission 1efore reaction After reaction -7uation )otal ato"ic "ass

239

1

145

Pu + 0n

94

280.0602 a.".u

56

93

1

Ba + 38Sr + 2 0n + energy

23.430 a.".u

)able belo* sho*s an e7uation of a reaction and total ato"ic "ass before and after a nuclear fusion. =uclear fusion 1efore reaction -7uation )otal ato"ic

2

3

H + 1H

1

4.030'3 a.".u

After reaction 4

❑

1

He ❑+ 2 0n + energy

2

4.0'083a.".u


Mr. Kenneath Y.

"ass a i. !hat is "eant by nuclear fission% &' "ark(

ii. :sing only the infor"ation given in the tables above, co"pare nuclear fission and nuclear fusion. ence state the relationship bet*een "ass and energy evolved. &4 "arks(

b =uclear fission produces a chain reaction. >escribe ho* the chain reaction happens in a nuclear fission of an ato" of uraniu". &8 "arks(

c A paint producing factory *ants to develop a volu"e control syste" *hich can ensure the 7uantity of paint in every tin is *ithin a specific range. )he tins of paint are transported on conveyor belt as sho*n in the figure belo*. +f the volu"e of the paint is less or "ore than the specific range of volu"e, the tin *ill be separated auto"atically.

:sing your kno*ledge and radioactivity and figure above, e9plain i. )he radioactive "aterial and e7uip"ent to develop the volu"e control ii. syste" iii. o* the e7uip"ent is asse"bled iv. o* the syste" *orks &'0 "arks(


Mr. Kenneath Y.

SPM 2006 . ?adioactive "aterial has so"e uses in the "edical field such as in the investigation of internal organs and in the sterili@ation of e7uip"ents.

a A doctor conducts an investigation on a patient$s kidney by inecting iodine/'3' radioisotope, that has a half life of  days, into the blood circulation. A nor"al kidney can e9pel the radioisotope in 20 "inutes. )he presence of radioisotope in the left and right kidneys is sho*n in the graph belo*. i. !hat is "eant by half life% &' "ark( ii.

1ased on the graphs in diagra" above, *hich kidney is not functioning properly% ive one reason. &2 "arks(

iii.

)he initial iodine/'3' activity is '600 counts per second. alculate the ti"e taken for the iodine/'3' activity to decrease to '00 counts per second. &2 "arks(

b Medical e7uip"ent is sterili@ed by radiation fro" a radioactive source. Bou are assigned to study the characteristics of so"e


Mr. Kenneath Y.

radioisotopes that are suitable for use in the sterili@ation of "edical e7uip"ent. )able sho*s the characteristics of five radioisotopes. ?adioisotope

haracteristics of isotope State of )ype of ray "atter Solid 1eta Solid a""a as 1eta i7uid a""a Solid Alpha

alf life

Strontiu"/0 2 years obalt/60 4 years 5enon/'33 4 days +odine/'3'  days Poloniu"/ '80 days 2'0 i. -9plain the suitability of the characteristics of the radioisotope to be used in the sterili@ation of "edical e7uip"ent. &6 "arks(

ii.

>eter"ine the "ost suitable radioisotope to be used and give one reason for your choice. &2 "arks(

c a""a rays can produce an effect in photographic fil". -9plain *hether ga""a rays is suitable to be used in taking photographs of an organ in hu"ans. &3 "arks(

SPM 200 . >iagra" belo* sho*s the rate of decay of radioactive 9enon/'33 and iodine/'3' respectively.


Mr. Kenneath Y.

a i. !hat is the "eaning of radioactive decay% &' "ark( ii. 1ased on the diagra"s above, co"pare the shape of the graph, the *ay the activity changes *ith ti"e and the ti"e taken for the activity to beco"e half of its original activity. =a"e the ti"e for the activity to decrease to half of its original activity. &4 "arks(

b !hy is an isotope that e"its alpha particles not suitable for use as a tracer in "edicine% &8 "arks(

c ?adiotheraphy is used in the treat"ent of cancer. )he radioactive ray used can cause side effects to the patient. :sing the kno*ledge about radioactivity, e9plain the steps taken to reduce the side effects. +n your e9planation, e"phasi@e the aspects ofC i. )he type of ray used ii. o* the radioactive radiation is targeted on the cancer cells. iii. )he dosage of the ray re7uired. iv. )he ti"e of the ray e9posure. &'0 "arks(

SPM 20'' '0. a >iagra" '2.' sho*s t*o types of tracks for"ed in a cloud cha"ber. )he tracks are for"ed due to the radiation fro" the radioisotope.


i. ii. iii.

Mr. Kenneath Y.

!hat is the "eaning of radioisotope% &' "ark( =a"e the radiation that causes the tracks in cloud cha"ber M and cloud cha"ber =% &2 "arks( -9plain your ans*er in aii. &2 "arks(

b ?adioisotope is used as a tracer to deter"ine the rate of absorption of fertili@ers by plants. Bou are re7uired to investigate the characteristics of radioisotopes as sho*n in table '2.

-9plain the suitability of each characteristics of the radioisotope to be used as a tracer. >eter"ine the "ost suitable radioisotope that can be used to


Mr. Kenneath Y.

detect the rate of absorption of fertili@er by plants. ive reasons for your choice. &'0 "arks( c A nuclear reaction is represented by the follo*ing e7uationC

1ased on the e7uation, calculateC i. ii.

the "ass defect &2 "arks( the energy released &3 "arks(

SPM 200 ''. >iagra" '0.' and '0.2 sho* the deflection of a radioactive e"ission in an electric field.


Mr. Kenneath Y.

a !hat is the "eaning of radioactivity% &' "ark( b :sing >iagra" '0.' and '0.2, i. state the charge of the radioactive e"ission &' "ark( ii. co"pare the voltage of the -) and the deflection of the radioactive e"ission. &' "arks( c State the relationship bet*een i. the voltage of the -) and the strength of the electric field bet*een the plates. &' "ark( ii. the strength of the electric field bet*een the plates and the deflection of the radioactive e"ission. &' "ark( d >iagra" '0.3 sho*s a type of nuclear reaction.

i. ii.

=a"e this type of nuclear reaction. &' "ark( -9plain ho* nuclear energy is produced fro" the nuclear reaction sho*n in >iagra" '0.3 &3 "arks( e >iagra" '0.8 sho*s ho* a radioactive source is being handled by a student.


Mr. Kenneath Y.

)he "ethod sho*n is not safe. Suggest and e9plainC i. ii. iii.

)he e7uip"ent to be used in handling a radioactive source Modifications to the storing "ethod to ensure safe keeping of the radioactive source Dther precautions that need to be taken *hen handling a radioactive source. &'0 "arks(


Mr. Kenneath Y.

SPM 2003

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