Atomic and Nuclear-Standard

8/19/2019 Atomic and Nuclear-Standard

1/68

1. Which one of the following correctly gives the number of electrons, protons and neutrons in a

neutral atom of the nuclideCu6529 ?

Number of electrons Number of protons Number of neutrons

A 65 29 !6

" !6 !6 29

C 29 29 65

# 29 29 !6

(1)

2. $n the %eiger&'arsden e(periment, α particles are scattered by gold nuclei )he e(perimental

results indicate that most α particles are

A scattered only at small angles

" scattered only at large angles

C absorbed in the target

# scattered bac* along the original direction

(1)

3. A sample of radioactive carbon&+ decays into a stable isotope of nitrogen As the carbon&+

decays, the rate at which the amount of nitrogen is produced

A decreases linearly with time

" increases linearly with time

C decreases e(ponentially with time

# increases e(ponentially with time

(1)

1


2/68

4. )he unified mass unit is defined as

A the mass of one neutral atom of+2

6 C

" +2+

of the mass of one neutral atom of+2

6 C

C 6

+

of the mass of one neutral atom of+2

6 C

# the mass of the nucleus of+2

6 C

(1)

5. )his -uestion is about nuclear reactions

.a/ Complete the table below, by placing a tic* . / in the relevant columns, to show how an

increase in each of the following properties affects the rate of decay of a sample of

radioactive material

PropertyEffect on rate of decay

increase decrease stays the same

temperature of sample

pressure on sample

amount of sample

(2)

0adium&226 .

22611

0a/ undergoes natural radioactive decay to disintegrate spontaneouslywith the emission of an alpha particle .α&particle/ to form radon .0n/ )he masses of the

particles involved in the reaction are

radium 226325 u

radon 2223+46 u

α&particle 3326 u

.b/ .i/ Complete the nuclear reaction e-uation below for this reaction

226

11 0a →

0n

(2)

2


3/68

.ii/ Calculate the energy released in the reaction

(3)

.c/ )he radium nucleus was stationary before the reaction

.i/ 7(plain, in terms of the momentum of the particles, why the radon nucleus and the

α&particle move off in opposite directions after the reaction

(3)

.ii/ )he speed of the radon nucleus after the reaction is v0 and that of the α&particle is

vα 8how that the ratio0

v

vα

is e-ual to 555

(3)

3


4/68

.iii/ sing the ratio given in .ii/ above, deduce that the *inetic energy of the radon

nucleus is much less than the *inetic energy of the α&particle

(3)

.d/ :ot all of the energy of the reaction is released as *inetic energy of the α&particle and of

the radon nucleus 8uggest one other form in which the energy is released

(1)

Another type of nuclear reaction is a fusion reaction )his reaction is the main source of the

8un;s radiant energy

.e/ .i/ 8tate what is meant by a fusion reaction

(3)

4


5/68

.ii/ 7(plain why the temperature and pressure of the gases in the 8un;s core must both

be very high for it to produce its radiant energy


6/68


7/68

.c/ $n total, there are appro(imately +329

electrons in the atoms ma*ing up a person

.i/ 7stimate the electrostatic force of repulsion between two people standing +33 m

apart as a result of these electrons

(4)

.ii/ 7(plain why two people standing +33 m apart would not feel the force that you

have calculated in part .i/

(2)

(Total 11 marks)

7


8/68

!. Which one of the following correctly identifies the atomic .proton/ number and mass .nucleon/

number of a nucleus that has neutrons n and protons p?

"tom#c number $ass number

A p n

" p n + p

C n p

# n + p p

(1)

%. )his -uestion is about nuclear reactions

.a/ .i/ #istinguish between fission and radioactive decay

(4)

A nucleus of uranium&2!5 .2!5

92 / may absorb a neutron and then undergo fission to produce

nuclei of strontium&93 .8r 93

!1 / and (enon&+2 .>e+,2

5, / and some neutrons

)he strontium&93 and the (enon&+2 nuclei both undergo radioactive decay with the emission of β

particles

.ii/ Write down the nuclear e-uation for this fission reaction

(2)

8


9/68

.iii/ 8tate the effect, if any, on the mass number .nucleon number/ and on the atomic

number .proton number/ of a nucleus when the nucleus undergoes β

decay

'ass number

Atomic number

(2)

)he uranium&2!5 nucleus is stationary at the time that the fission reaction occurs $n this fission

reaction, +91 'e@ of energy is released =f this total energy, +32 'e@ and 65 'e@ are the

*inetic energies of the strontium&93 and (enon&+2 nuclei respectively

.b/ .i/ Calculate the magnitude of the momentum of the strontium&93 nucleus

(4)

.ii/ 7(plain why the magnitude of the momentum of the strontium&93 nucleus is note(actly e-ual in magnitude to that of the (enon&+2 nucleus

(2)

=n the diagram below, the circle represents the position of a uranium&2!5 nucleus before

fission )he momentum of the strontium&93 nucleus after fission is represented by the arrow

s t r o n t i u m & 9 3

9


10/68

10


11/68

.iii/ =n the diagram above, draw an arrow to represent the momentum of the (enon&+2

nucleus after the fission

(2)

.c/ $n a fission reactor for the generation of electrical energy, 25 of the total energy

released in a fission reaction is converted into electrical energy

.i/ sing the data in .b/, calculate the electrical energy, in Boules, produced as a result

of nuclear fission of one nucleus

(2)

.ii/ )he specific heat capacity of water is 2 +3! D Eg

+E

+ Calculate the energy

re-uired to raise the temperature of 253 g of water from 23FC to its boiling point

.+33FC/

(3)

.iii/ sing your answer to .c/.i/, determine the mass of uranium&2!5 that must be

fissioned in order to supply the amount of energy calculated in .c/.ii/ )he mass of

a uranium&2!5 atom is !9 +3 25

*g

(4)

(Total 25 marks)

11


12/68

12


13/68

1&. )his -uestion is about charged particles in a magnetic field

A beam of singly ioniGed atoms moving at speed v enters a region of magnetic field strength B

as shown below

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

d i r e c t i o n o f m o t i o no f i o n i G e d a t o m s

u n i f o r m m a g n e t i c f i e l di n t o p l a n e o f p a p e r

)he magnetic field is directed into the plane of the paper )he ions follow a circular path,

.a/ #educe that the radius r of the circular path is given by

r H Bq

mv

where m and q are the mass and charge respectively of the ions

(2)

$n one particular e(periment, the beam contains singly ioniGed neon atoms all moving at the

same speed =n entering the magnetic field, the beam divides in two )he path of the ions of

mass 23 u has radius +53 cm

.b/ Calculate in terms of u, the mass of the ions having a path of radius +65 cm

(2)

13


14/68

)he atomic number .proton number/ of neon is +3

.c/ 8tate the number of protons and neutrons in each type of neon ion

(2)

(Total 6 marks)

11. )he presence of neutrons inside the nucleus is supported by the e(istence of

A isotopes

" orbiting electrons

C gamma radiation

# neutral atoms

(1)

12. )he source of the 8un;s energy is

A fission

" radioactivity

C fusion

# ioniGation

(1)

14


15/68

13. )his -uestion is about nuclear binding energy

.a/ .i/ #efine nucleon

(1)

.ii/ #efine nuclear binding energy of a nucleus

(1)

)he a(es below show values of nucleon number A .horiGontal a(is/ and average binding energy

per nucleon E .vertical a(is/ ."inding energy is ta*en to be a positive -uantity/

9

1

4

6

5

,

!

2

+

33 2 5 5 3 4 5 + 3 3 + 2 5 + 5 3 + 4 5 2 3 3 2 2 5 2 5 3

A

E I ' e @

.b/ 'ar* on the E a(is above, the appro(imate position of

.i/ the isotopeJe56

26 .label this J/

(1)

15


16/68

.ii/ the isotope


17/68

.ii/ se your graph in .c/ to e(plain why energy is released in this reaction

(2)

(Total 13 marks)

14. )he e(istence of isotopes provides evidence for the presence of

A electrons in atomic energy levels

" electrons in the nuclei of atoms

C neutrons in the nuclei of atoms

# protons in the nuclei of atoms

(1)

15. )his -uestion is about radioactivity and nuclear energy

.a/ #efine the following terms,

.i/ Isotope

(1)

.ii/ Radioactive half-life

(1)

17


18/68

)horium&224 .)h&224/ results from the decay of the isotope actinium&224

.b/ .i/ Complete the following reaction e-uation

+→ )hAc 22493

224

19

(1)

)h&224 has a half&life of +1 days and undergoes a&decay to the isotope 0a&22! .0a&22!/ A

sample of )h&224 has an initial activity of !2 arbitrary units

.ii/ sing the a(es below, draw a graph to show the variation with time t .for t H 3 to

t H 42 days/ of the activity A of )h&224

! 2

2 ,

+ 6

1

33 + 1 ! 6 5 , 4 2

a c t i v i t y Ia r b i t r a r y u n i t s

t i m e I d a y s

(2)

.iii/ #etermine from your graph, the activity of thorium after 53 days

(1)

18


19/68

.iv/ =utline the e(perimental procedure to measure the activity of )h&224

(2)

$n the decay of a )h&224 nucleus, a &ray photon is also emitted

.c/ se the following data to deduce that the energy of the &ray photon is 3664 'e@

mass of )h&224 nucleus H 2243241 u

mass of 0a&22! nucleus H 22!3+16 u

mass of helium nucleus H 3326 u

energy of α&particle emitted H51+ 'e@

unified atomic mass unit .u/ H 9!+5 'e@ c 2

Kou may assume that the )h&224 nucleus is stationary before decay and that the 0a&22!

nucleus has negligible *inetic energy

(3)

(Total 11 marks)

19


20/68

16. Ag&+32, Ag&+3! and Ag&+3 are three isotopes of the element silver

Which one of the following is a true statement about the nuclei of these isotopes?

A All have the same mass

" All have the same number of nucleons

C All have the same number of neutrons

# All have the same number of protons

(1)

1. )his -uestion is about radioactive decay

A nucleus of the isotope (enon, >e&+!+, is produced when a nucleus of the radioactive isotope

iodine $&+!+ decays

.a/ 7(plain the term isotopes

(2)

.b/ Jill in the bo(es below in order to complete the nuclear reaction e-uation for this decay

+ ! ++ ! +$ > e

5 , ?

(2)

20


21/68

.c/ )he activity A of a freshly prepared sample of the iodine isotope is !2 +35 "- )he

variation of the activity A with time t is shown below

! 5

! 3

2 5

2 3

+ 5

+ 3

3 5

33 5 3 + 3 + 5 2 3 2 5 ! 3 ! 5 , 3 , 5

t I d a y s

A I + 3 " -5

#raw a best&fit line for the data points

(1)

.d/ se the graph to estimate the half&life of $&+!+

(1)

(Total 6 marks)

21


22/68

1!. )his -uestion is about atomic models )he diagram below .not to scale/ shows a simple model

of the hydrogen atom in which the electron orbits the proton in a circular path of radius R

e l e c t r o nc h a r g e ? e

p r o t o nc h a r g e e

R

.a/ =n the diagram, draw an arrow to show the direction of

.i/ the acceleration of the electron .label this A/L

(1)

.ii/ the velocity of the electron .label this @/

(1)

.b/ 8tate an e(pression for the magnitude of the electrostatic force ! acting on the electron

(1)

22


23/68

.c/ )he orbital speed of the electron is 22 +36 m s

+

#educe that the radius R of the orbit is 52 +3 ++

m

(3)

.d/ A more comple( model of the atom suggests that the orbital radius can only ta*e certain

discrete values )his leads to the idea of discrete energy levels within the atom =utline

the evidence that supports the e(istence of discrete energy levels

(3)

(Total % marks)

23


24/68

1%. )he emission and absorption spectra of different elements provides evidence for the e(istence of

A isotopes

" neutrons

C protons

# atomic energy levels

(1)

2&. Which of the following gives the correct number of protons and number of neutrons in the

nucleus of "?++5

Number of protons Number of neutrons

A 5 6

" 5 ++

C 6 5

# ++ 5

(1)

21. )he unified mass unit is defined as the rest mass of

A a proton

" an atom of carbon&+2 divided by +2

C an atom of carbon&+2

# an atom of hydrogen&+

(1)

24


25/68

22. )his -uestion is about collisions and radioactive decay

.a/ .i/ #efine linear momentum and impulse

Minear momentum

$mpulse

(2)

.ii/ 8tate the law of conservation of momentum

(2)

.iii/ sing your definitions in .a/.i/, deduce that linear momentum is constant for an

obBect in e-uilibrium

(2)

A stationary radon&223 .0n22316 / nucleus undergoes α&decay to form a nucleus of polonium .No/

)he α&particle has *inetic energy of 629 'e@

.b/ .i/ Complete the nuclear e-uation for this decay

0n22316 → No +

(2)

25


26/68

.ii/ Calculate the *inetic energy, in Boules, of the α&particle

(2)

.iii/ #educe that the speed of the α&particle is +4 +34 m s

+

(1)

)he diagram below shows the α&particle and the polonium nucleus immediately after the decay

)he direction of the velocity of the α&particle is indicated

& p a r t i c l e

p o l o n i u m n u c l e u s

.c/ .i/ =n the diagram above, draw an arrow to show the initial direction of motion of the

polonium nucleus immediately after the decay

(1)

.ii/ #etermine the speed of the polonium nucleus immediately after the decay

(3)

26


27/68

.iii/ $n the decay of another radon nucleus, the nucleus is moving before the decay

Without any further calculation, suggest the effect, if any, of this initial speed on

the paths shown in .c/.i/

(2)

)he half&life of the decay of radon&223 is 55 s

.d/ .i/ 7(plain why it is not possible to state a time for the life of a radon&223 nucleus

(2)

.ii/ #efine half-life

(2)

27


28/68

A sample of radon&223 has an initial activity A3

.iii/ =n the a(es below, draw a graph to show the variation with time t of the activity A

for time t H 3 to time t H +13 s

A

A 3

3

3 , 3 1 3 + 2 3 + 6 3 2 3 3t sI

(2)

.iv/ se your graph to determine the activity, in terms of A3, of the sample of radon at

time t H +23 s Also, estimate the activity, in terms of A3, at time t H !!3 s

Activity at time t H +23 s

Activity at time t H !!3 s

(2)

(Total 25 marks)

28


29/68

23. )his -uestion is about radioactive decay and the age of roc*s

A nucleus of the radioactive isotope potassium&3 decays into a stable nucleus of argon&3

.a/ Complete the e-uation below for the decay of a potassium&3 nucleus

+→ Ar E 3+1

3+9

(2)

A certain sample of roc*s contains +2 +3 6

g of potassium&3 and 43 +3 6

g of trapped

argon&3 gas

.b/ Assuming that all the argon originated from the decay of potassium&3 and that none has

escaped from the roc*s, calculate what mass of potassium was present when the roc*swere first formed

(1)

)he half&life of potassium&3 is +! +39 years

.c/ #etermine

.i/ the decay constant of potassium&3L

(2)

.ii/ the age of the roc*s

(2)

(Total marks)

29


30/68

30


31/68

24. Which one of the following provides evidence for a nuclear model of the atom?

A :atural radioactive decay

" )he ioniGing properties of radiation

C )he stability of certain elements

# )he scattering of alpha particles by gold foil

(1)

25. )he main source of the 8un;s energy is

A chemical reaction

" natural radioactivity

C nuclear fusion

# nuclear fission

(1)

26. :uclear binding energy and nuclear decay

.a/ 8tate what is meant by a nucleon

(1)

.b/ #efine what is meant by the binding energy of a nucleus

(1)

31


32/68

)he graph below shows the variation with nucleon .mass/ number of the binding energy per

nucleon

"

i n

d

i n

g

e n

e r

g

y

p

e r

n

u

c l e o

n

I

'

e @

+ 3

9

1

4

6

5

,

!

2

+

3

5 6

J e + ! 1 " a

+ 6

= 2 3 1

N b

2 ! 5

9

" e

6

M i

!<

2 <

3 5 3 + 3 3 + 5 3 2 3 3 2 5 3

: u c l e o n n u m b e r

.c/ se the graph to e(plain why energy can be released in both the fission and the fusion

processes

(3)

32


33/68

.d/ A sample of carbon&++ has an initial mass of 3 × +3 +5

*g Carbon&++ has a half&life of

appro(imately 23 minutes Calculate the mass of carbon&++ remaining after one hour has

elapsed

(2)

.e/ ranium&2!1,,2!192 undergoes a&decay to form an isotope of thorium Write down the

nuclear e-uation for this decay

(2)

(Total % marks)

2. )he initial activity of a sample of a radioactive isotope of half&life +3 hours is A What is the age

of the sample when its activity is?

!2

A

A !3 hours

" 3 hours

C 53 hours

# !23 hours

(1)

33


34/68

2!. )wo light nuclei of masses m+ and m2 fuse in a nuclear reaction to form a nucleus of mass "

Which of the following e(pressions correctly relates the masses of the nuclei?

A " O m+ m2

" " P m+ m2

C " H m+ m2

# " H m+ Q m2

(1)

2%. 0adioactive decay

.a/ Carbon&+ is a radioactive isotope with a half&life of 5533 years $t is produced in the

atmosphere by neutron bombardment of nitrogen )he e-uation for this reaction is

>Cn : +,6+

3

+,

4 +→+

.i/ 7(plain what are meant by isotopes

(1)

.ii/ #efine the term radioactive half-life

(1)

.iii/ $dentify the particle >

(1)

34


35/68

.b/ Miving trees contain atoms of carbon&+ )he activity per gram of carbon from a living

tree is higher than that per gram of carbon&+ from burnt wood .charcoal/ found at an

ancient campsite

.i/ A living tree continuously ta*es in carbon dio(ide from the atmosphere 8uggst

why the activity of the carbon from the charcoal is less than that of the livingwood

(3)

.ii/ 7ach gram of a living tree contains appro(imately + × +3 +2

g of the isotope

carbon&+ #educe that each gram of carbon in living wood contains appro(imately

× +3+3

atoms of carbon&+

(2)

35


36/68

.c/ =n the grid below, draw a graph to show the variation with time of the number of carbon&

+ atoms in one gram of wood from a tree Kour graph should indicate the number of

atoms for a period of +1 × +3 years after the tree has died .


37/68

3&. )he nuclear notation for cadmium&++ isCd++,,1 Which one of the following correctly shows

the composition of this nucleus?

Number of protons Number of neutrons Number of nucleons

A 1 66 ++

" 1 ++ +62

C 66 1 ++

# 66 1 +62

(1)

31. )his -uestion is about nuclear energy

.a/ #efine nuclear binding energy

(2)

.b/ A neutron collides with a nucleus of uranium&2!5 and the following reaction ta*es place

n2Cs0bn +3+!1

5596!4

+3

2!592 ++→+

8tate the name of this type of reaction

(1)

37


38/68

.c/ )he mass of nuclei can be e(pressed in terms of unified mass units .u/

.i/ #efine the term unified mass unit

(1)

.ii/ sing the data below, calculate the energy, in 'e@, that is released in the reaction

u3!92!5of mass 2!592 =

u9!2950bof mass 96!4 =

u9++2+!4Csof mass +!155 =

u3314+nof mass +3 =

(4)

.d/ 7(plain the importance of the two neutrons produced in the reaction

(2)

.e/ 7ach neutron accounts for about 2 'e@ of the energy released in the reaction 8uggest

what accounts for the rest of the energy released

38


39/68

(2)

.f/ )he reaction in .b/ is more li*ely to ta*e place if the colliding neutron has an energy of

about 3+ e@ $n certain types of nuclear reactors in which this reaction might ta*e place,

the neutrons produced have their energy reduced by collisions with nuclei of graphite

.+2C/ )he law of conservation of momentum can be used to estimate the number ofcollisions re-uired to reduce the energy of the neutrons to 3+ e@

8tate the law of conservation of momentum

(2)

.g/ A neutron has a *inetic energy of 233 'e@ #educe that the speed of the neutron is +95

× +34 m s

Q+

(2)

39


40/68

.h/ Kou may assume that the mass of a nucleus of graphite is twelve times the mass of a

neutron $n a certain collision between a neutron and a stationary graphite nucleus, the

neutron of *inetic energy 233 'e@, rebounds from the graphite nucleus in a direction

along a line Boining the centres of the nucleus and neutron

b e f o r e c o l l i s i o n a f t e r c o l l i s i o n

g r a p h i t e

n e u t r o n

+ 9 5 + 3 m s4 ? + v H 3 ! 3 3 + 3 m s ? +4+ 6 5 + 3 m s4 ? +

)he rebound speed of the neutron is +65 × +34 m s

Q+

.i/ #educe that the speed v of the graphite nucleus after collision is 3!33 × +34 m sQ+

(3)

.ii/ sing your answer in .i/, deduce whether the collision is elastic or inelastic

(3)

40


41/68

.iii/ se your answer to .ii/ to deduce that each time a neutron collides in this manner

with a graphite nucleus it loses about !3 of its *inetic energy

(2)

.iv/ 8tate the fraction of the total initial energy lost by a neutron in its second collision

with a graphite nucleus

(1)

(Total 25 marks)

32. A sample of material contains 6 mg of a radioactive isotope After si(ty minutes 23 mg of the

isotope remain )he half&life of this isotope is

A +3 minutes

" +2 minutes

C +5 minutes

# 23 minutes

(1)

41


42/68

33. )he binding energy per nucleon of the nucleusMi4! is appro(imately 5 'e@ )he total energy

re-uired to completely separate the nucleons of this nucleus is appro(imately

A +5 'e@

" 23 'e@

C !5 'e@

# 53 'e@

(1)

34. )his -uestion is about nuclear binding energy

)he table below gives the mass defect per nucleon of deuterium( )


43/68

.b/ Calculate the energy, in Boule, that is released when two deuterium nuclei fuse to form a

helium& nucleus

(4)

(Total 6 marks)

35. 0adioactivity

=ne isotope of potassium is potassium&2( )E ,2+9 :uclei of this isotope undergo radioactive

decay with a half&life of +25 hours to form nuclei of calcium

.a/ 8tate what is meant by the term isotopes

(2)

.b/ Complete the nuclear reaction e-uation for this decay process

+→ CaE 23,2

+9

(2)

43


44/68

.c/ )he graph below shows the variation with time of the number : of potassium&2 nuclei

in a particular sample

#

# 3

+

2 3 #

33 + 3 2 3 ! 3 , 3 5 3 6 3 4 3

t I h o u r s

)he isotope of calcium formed in this decay is stable

=n the graph above, draw a line to show the variation with time t of the number of

calcium nuclei in the sample

(1)

44


45/68

.d/ se the graph in .c/, or otherwise, to determine the time at which the ratio

sampleinnuclei,2& potassiumof number

sampleinnucleicalciumof number

is e-ual to 43

(2)

(Total marks)

45


46/68

36. Which of the following provides evidence for the e(istence of neutrons?

A )he %eiger&'arsden e(periment

" $sotopes

C :atural radioactive decay

# Artificial transmutations of elements

(1)

3. )he e-uation of a nuclear reaction is shown below

n


47/68

.b/ $n the 0utherford&%eiger&'arsden e(periment to investigate the structure of the atom, a&

particles were directed towards a gold foil 7(plain why a&particles, rather than electrons,

were used in this e(periment

(2)

.c/ ranium&2!1

( 2!192undergoes a&decay to form thorium .)h/ )he half&life of uranium

2!192 is 5 × +39 years

.i/ #efine half-life

(2)

.ii/ Write down the nuclear e-uation for the a&decay of uranium to thorium

(2)

.d/ )horium is radioactive and further decays occur, eventually giving lead which is stable

)hese further decays all occur within a time that is short compared to the half&life of

2!192 $n a sample of roc*s the ratio of the number of uranium atoms to the number of

lead atoms is 4

+

.i/ 7stimate the age of the roc*s assuming that no lead was initially present in the

roc*s

(2)

47


48/68

48


49/68

.ii/ 8tate one further assumption that is made in this estimate

(1)

(Total 1& marks)

3%. Which of the following provides evidence for the e(istence of atomic energy levels?

A )he absorption line spectra of gases

" )he e(istence of isotopes of elements

C 7nergy release during fission reactions

# )he scattering of R &particles by a thin metal film

(1)

4&. Which of the following statements best describes the random nature of radioactive decay?

A )he decaying nucleus emits either an a&particle, or a b&particle or a g&ray photon

" )he type of radiation emitted by the decaying nucleus cannot be predicted

C )he time at which a particular nucleus will decay cannot be predicted

# )he decay of a nucleus is unaffected by environmental conditions

(1)

49


50/68

41. )he graph below illustrates the variation with nucleon number .mass number/ # of the binding

energy per nucleon E of nuclei

Which of the labelled nuclei is the most stable?

A

"

C

#

E

#

(1)

42. 0adioactive decay

.a/ )he nucleon number .mass number/ of a stable isotope of argon is !6 and of a radioactive

isotope of argon is !9

.i/ 8tate what is meant by a nucleon

(1)

50


51/68

.ii/ 7(plain, in terms of the number of nucleons and the forces between them, why

argon&!6 is stable and argon&!9 is radioactive

(4)

.b/ A particular nucleus of argon&!9 undergoes the decay shown by the nuclear reactione-uation below

−

+→ β E Ar !9

+1

.i/ 8tate the proton .atomic/ number and the nucleon .mass/ number of the potassium

.E/ nucleus

Nroton number

:ucleon number

(2)

.ii/ se the following data to determine the ma(imum energy, in D, of the bQ particle in

the decay of a sample of argon&!9

'ass of argon&!9 nucleus H !196!+ u

'ass of E nucleus H !196!43 u

(3)

51


52/68


53/68

43. )he initial activity .rate of decay/ of a sample of mass 25 mg of a radioactive isotope is A3 )he

half&life of the isotope is .

2

+$ Which of the following gives the initial activity and half&life of a

sample of mass 53 mg of this isotope?

"ct##ty alf*l#fe

A A32

+$

" 2 A32

+$

C A32

+2$

# 2 A32

+2$

(1)

44. A neutron is captured by a nucleus Which of the following gives the changes in the atomic

.proton/ number and mass .nucleon/ number of the nucleus?

"tom#c number $ass number

A unchanged unchanged

" unchanged increases by +

C increases by + unchanged

# increases by + increases by +

(1)

53


54/68

45. :uclear reactions

.a/ .i/ 8tate what is meant by radioactive decay

(2)

.ii/ 0adioactive decay is said to be a random process 8tate what is meant by random

decay

(2)

.b/ $n +9+9, 0utherford was investigating the bombardment of nitrogen by R&particles


55/68

Calculate the minimum energy, in 'e@, of an a&particle re-uired to cause this

transformation to occur 7(plain your answer

(4)

(Total 1& marks)

46. Which of the following provides evidence for the e(istence of atomic energy levels?

A Alpha&particle scattering

" Continuous emission spectra

C #iscrete energies of gamma radiation

# Mine absorption spectra

(1)

4. :uclide > has a half&life of + day and nuclide K has a half&life of 5 days $n a particular sample,

the activities of > and K are found to be e-ual

When the activity is tested again after +3 days, the activity will be

A entirely due to nuclide >

" due e-ually to nuclides > and K

C mostly due to nuclide >

# mostly due to nuclide K

(1)

55


56/68

4!. )his -uestion is about nuclear reaction

.a/ 8tate the meaning of the terms

.i/ nuclide

(2)

.ii/ isotope

(1)

.b/ A nucleus of :a2++ undergoes radioactive decay to the stable nucleus

'g2+2

.i/ $dentify this type of radioactive decay

(1)

.ii/ se the data below to determine the rest mass in atomic mass unit of the particle

emitted in the decay of :a2++

rest mass of :a2++ H 2!99396u

rest mass of 'g2,+2 H 2!9153u

energy released in decay H 5332+63 'e@

56


57/68

(3)

.c/ )he isotope sodium&2 is radioactive but the isotope sodium&2! is stable 8uggest which

of these isotopes has the greater nuclear binding energy

(2)

.d/ At time t H 3, a sample of sodium&2 contains # 3 atoms of sodium&2 )he half&life of

sodium&2 is 2+$

.i/ sing the a(es below, draw a s*etch graph to show the variation with time t of the

number # of sodium&2 atoms in the sample

33

$ 2 $ ! $ t

#

#

+222

++

3

(2)

.ii/ 8tate how the rate at which the sample is decaying at any time t can be found from

your s*etch graph

(1)

(Total 12 marks)

57


58/68

4%. A nuclide > has a half&life of +3 s =n decay the stable nuclide K is formed $nitially a sample

contains only atoms of >

After what time will 145 of the atoms in the sample have decayed into nuclide K

A 93 s

" !3 s

C 43 s

# 13 s

(1)

5&. Which of the following best describes why alpha&particles travel only a short distance in air?

A )hey undergo radioactive decay

" )hey undergo elastic collisions with air molecules

C )hey ioniGe air molecules

# )hey are attracted by the nuclei of air molecules

(1)

51. A nucleus 8r 93

!1 decays by the emission of an electron What are the mass .nucleon/ number and

the atomic .proton/ number of the resulting nucleus?

$ass number Proton number

A 19 !1

" 93 !9

C 9+ !1

# 9+ !9

(1)

58


59/68

52. )his -uestion is about nuclear decay

.a/ .i/ #escribe the phenomenon of natural radioactive decay

(3)

.ii/ $oniGing radiation is emitted during radioactive decay 7(plain what is meant by

the term ioniGing

(2)

.b/ )he s*etch graph below shows the variation with mass number .nucleon number/ A of the binding energy per nucleon E of nuclei

E

A

=ne possible nuclear reaction that occurs when uranium&2!5 is bombarded by a neutron

to form (enon&+2 and strontium&93 is represented as

:8r >en +393!1

+25

+3

2!592 ++→+

.i/ $dentify the type of nuclear reaction represented above

(1)

59


60/68

.ii/ =n the s*etch graph above, identify with their symbols the appro(imate positions

of the uranium ./, the (enon .>e/ and the strontium .8r/ nuclei

(2)

.iii/ #ata for the binding energies of (enon&+2 and strontium&93 are given below

#sotope b#nd#n+ ener+y ' $e,

(enon&+2

strontium&93

++19

411

)he total energy released during the reaction is +149 'e@ #etermine the binding

energy per nucleon of uranium&2!5

(3)

.iv/ 8tate why binding energy of the neutrons formed in the reaction is not -uoted

(1)

(Total 12 marks)

53. )he initial activity of a sample of a radioactive isotope of half&life +3 hours is A What is the age

of the sample when its activity is?

!2

A

A !3 hours

" 3 hours

C 53 hours

# !23 hours

(1)

60


61/68

54. When the isotope aluminium&24 is bombarded with alpha particles, the following nuclear

reaction can ta*e place

neutron>Al?

Proton number Nucleon number

A +5 !3

" +6 !+

C !3 +5

# !+ +6

(1)

61


62/68

55. )his -uestion is about nuclear power production

.a/ )he purpose of a nuclear power station is to produce electrical energy from nuclear

energy )he diagram below is a representation of the principal components of a nuclear

reactor pile used in a certain type of nuclear power station that uses uranium as a fuel

)he function of the moderator is to slow down the neutrons produced in a reaction such

as that described above

7(plain,

.i/ why it is necessary to slow down the neutrons

(3)

.ii/ the function of the control rods

(2)

62


63/68

.b/ With reference to the concept of fuel enrichment in a nuclear reactor e(plain,

.i/ the advantage of enriching the uranium used in a nuclear reactor

(3)

.ii/ from an international point of view, a possible ris* to which fuel enrichment could

lead

(2)

63


64/68

.c/ A particular nuclear reactor uses uranium&2!5 as its fuel source When a nucleus of

uranium&2!5 absorbs a neutron, the following reaction can ta*e place

n28r >en +393

!1

+,,

5,

+

3

2!5

92 ++→+

)he following data are available

rest mass of2!592 H 2+195 × +3

5 'e@ c

2

rest mass of>e

+,,

5, H +!31 × +35 'e@ c

2

rest mass of8r 93!1 H 1!49 × +3

'e@ c

2

rest mass of

n+3 H 9!956 'e@ c

2

.i/ 8how that the energy released in the reaction is appro(imately +13 'e@

(1)

.ii/ 8tate the form in which the energy appears

(1)

64


65/68

.d/ )he energy released by + atom of carbon&+2 during combustion is appro(imately e@

.i/ sing the answer to .c/.i/, estimate the ratio

+2&carbonof densityenergy

2!5&uraniumof densityenergy

(3)

.ii/ 8uggest, with reference to your answer in .d/.i/, one advantage of uranium&2!5

compared with fossil fuels

(1)

65


66/68

.e/ When a uranium&2!1 nucleus absorbs a neutron the following reaction can ta*e place

n 2!992+

3

2!1

92 →+

)he isotope uranium&2!9 is radioactive and decays with a half&life of 2! minutes to forman isotope of neptunium&2!9 .:p&2!9/

.i/ #efine radioactive half-life and e(plain what is meant by an isotope

0adioactive half&life

$sotope

(2)

.ii/ Complete the reaction e-uation for this decay

→2!992

(3)

.iii/ )he isotope neptunium&2!9 undergoes radioactive b& decay to form an isotope of

plutonium =utline one advantage and one disadvantage of this decay in relation to

nuclear power production

Advantage

#isadvantage

(4)

(Total 25 marks)

66


67/68

56. 0adioactive decay

.a/ Carbon&+ is a radioactive isotope with a half&life of 5533 years $t is produced in the

atmosphere by neutron bombardment of nitrogen )he e-uation for this reaction is

>Cn : +,6+3

+,4 +→+

.i/ 7(plain what is meant by isotopes

(1)

.ii/ $dentify the particle >

(1)

.b/ 7ach gram of a living tree contains appro(imately × +3+3

atoms of carbon&+

=n the a(es below, draw a graph to show the variation with time of the number of carbon&

+ atoms in one gram of wood from a tree Kour graph should indicate the number of

atoms for a period of +1 × +3 years after the tree has died .


68/68

.c/ )he activity of a radioactive sample is proportional to the number of atoms in the sample

)he activity per gram of carbon from a living tree is 96 disintegrations per minute )he

activity per gram of carbon in burnt wood found at an ancient campsite is +9

disintegrations per minute

.i/ 7stimate the number of atoms of carbon&+ in the burnt wood

(1)

.ii/ Jrom the graph you have drawn in .b/, estimate the age of the burnt wood

(1)(Total marks)

Documents

Atomic and Nuclear-Standard