Topic 7 Summative [55 marks]
1.
[1 mark]
Markscheme
B
2.
[1 mark]
Markscheme
A
3.
[1 mark]
Markscheme
C
4.
[1 mark]
Markscheme
B
5.
[1 mark]
Markscheme
B
6.
[1 mark]
Markscheme
B
7.
[1 mark]
Markscheme
A
8.
[1 mark]
Markscheme
B
9.
[1 mark]
Markscheme
C
10.
[1 mark]
Markscheme
A
11.
[1 mark]
Markscheme
D
12.
[1 mark]
Markscheme
C
13.
[1 mark]
Markscheme
C
14.
[1 mark]
Markscheme
A
15.
[1 mark]
Markscheme
B
16.
[1 mark]
Markscheme
C
17a.
[2 marks]
Markscheme
30
15
P → (
+
0
+1
30
14
Si)
e + ve
✔
✔
Subscript on neutrino not necessary to award MP2.
Allow the use of β for e.
Do not allow an anti-neutrino for MP2.
17b.
[3 marks]
Markscheme
correct change of either u to d ✔
W+ shown ✔
correct arrow directions for positron and electron neutrino ✔
Allow ECF from MP2 in ai for MP3.
17c.
[2 marks]
Markscheme
quarks cannot be directly observed as free particles/must remain bound to other quarks/quarks cannot be isolated ✔
because energy given to nucleon creates other particles rather than freeing quarks/OWTTE ✔
17d.
[1 mark]
Markscheme
models need testing/new information may change models/new technology may bring new information/Models can be revised/OWTTE ✔
Look for responses that suggest changes/improvements to models.
Don’t accept answers specifically about the Standard Model.
Don’t accept answers about simply proving the model correct.
18a.
[1 mark]
Markscheme
proton /
1
1
H
/p✔
18b.
[2 marks]
Markscheme
«3 x 2.78 − 2 × 2 × 1.12»
See 3 × 2.78/8.34 OR 2 × 2 × 1.12/4.48✔
3.86 «MeV» ✔
18c.
[2 marks]
Markscheme
the deuterium nuclei are positively charged/repel ✔
high KE/energy is required to overcome «Coulomb/electrostatic» repulsion /potential barrier
OR
high KE/energy is required to bring the nuclei within range of the strong nuclear force ✔
high temperatures are required to give high KEs/energies ✔
18d.
[1 mark]
Markscheme
−1 / -e ✔
18e.
[1 mark]
Markscheme
−3 ✔
19a.
[1 mark]
Markscheme
energy required to «completely» separate the nucleons
OR
energy released when a nucleus is formed from its constituent nucleons ✓
Allow protons AND neutrons.
19b.
[1 mark]
Markscheme
the values «in SI units» would be very small ✓
19c.
[1 mark]
Markscheme
140 × 8. 29 + 94 × 8. 59 − 235 × 7. 59
OR 184 « MeV » ✓
19d.
[2 marks]
Markscheme
see «energy
7. 4 × 10
13
=
» 180 × 10
«J kg
−1
6
× 1. 60 × 10
−19
AND «mass
=
» 235 × 1. 66 × 10
−27
✓
»✓
19e.
[2 marks]
Markscheme
energy produced in one day
mass
=
2.9×10
7.4×10
14
13
= 3. 9
9
=
1.2×10 ×24×3600
0.36
= 2. 9 × 10
14
«J» ✓
« kg » ✓
19f.
[1 mark]
Markscheme
39
✓
Do not allow
94
39
X
unless the proton number is indicated.
19g.
[1 mark]
Markscheme
75
«s» ✓
19h.
[2 marks]
Markscheme
ALTERNATIVE 1
10 min= 8 t1/2
✓
mass remaining=
1. 0 × (
1
2
8
)
= 3. 9 × 10
−3
« kg » ✓
ALTERNATIVE 2
decay constant
=
mass remaining
«
ln 2
75
=
»9. 24 × 10
= 1. 0 × e
−9.24×10
−3
−3
×600
«s » ✓
−1
= 3. 9 × 10
−3
« kg » ✓
20a.
[1 mark]
Markscheme
the energy needed to «completely» separate the nucleons of a nucleus
OR
the energy released when a nucleus is assembled from its constituent nucleons ✓
Accept reference to protons and neutrons.
20b.
[2 marks]
Markscheme
curve rising to a maximum between 50 and 100 ✓
curve continued and decreasing ✓
Ignore starting point.
Ignore maximum at alpha particle.
20c.
[1 mark]
Markscheme
At a point on the peak of their graph ✓
20d.
[1 mark]
Markscheme
beta minus «decay» ✓
20e.
[3 marks]
Markscheme
correct mass numbers for uranium (234) and alpha (4) ✓
234 × 7. 600 + 4 × 7. 074 − 238 × 7. 568
«MeV» ✓
energy released 5.51 «MeV» ✓
Ignore any negative sign.
20f.
[2 marks]
Markscheme
p
KEα
« KE
=
»
p
U
2
2mα
2
2m
«
234
4
=
OR
mU
mα
✓
U
» 58. 5 ✓
Award [2] marks for a bald correct answer.
Accept
117
2
for MP2.
20g.
[3 marks]
Markscheme
number of nuclei present =
initial activity is λN0
33×10
238
= 2. 5 × 10
power is 2. 08 × 1016
3
× 6. 02 × 10
−10
× 5. 51 × 10
6
23
« = 8. 347 × 10 » ✓
× 8. 347 × 10
× 1. 6 × 10
25
25
−19
« = 2. 08 × 10
≈ 18
16
Bq
»✓
«kW» ✓
Allow a final answer of 20 kW if 6 MeV used.
Allow ECF from MP1 and MP2.
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