1.
State what is meant by the nuclear model.
[1 mark]
- tiny positive nucleus, electrons in shells
JD SCIENCE
Radioactivity
Indicative marking points. Award marks for equivalent scientific or mathematical wording. Do not issue this sheet with the student worksheet.
2.
State what is meant by an isotope.
[1 mark]
- same protons, different neutrons
3.
State what is meant by alpha radiation.
[1 mark]
- helium nucleus, 2+ , highly ionising, weakly penetrating
4.
State what is meant by beta radiation.
[1 mark]
- fast electron, stopped by aluminium
5.
State what is meant by gamma radiation.
[1 mark]
- electromagnetic wave
6.
State what is meant by half-life.
[1 mark]
- time for activity or undecayed nuclei to halve
7.
State what is meant by activity.
[1 mark]
- decays per second
8.
State what is meant by irradiation.
[1 mark]
- exposure to radiation from outside
9.
State what is meant by contamination.
[1 mark]
- radioactive material on or in an object
10.
State what is meant by nuclear fission.
[1 mark]
- splitting a large nucleus
11.
Owain is asked about the nuclear model in a WJEC Physics paper.
(a) [2 marks]
- most of the atom is empty space
(b) [3 marks]
- from alpha scattering
12.
Owain is asked about an isotope in a WJEC Physics paper.
(a) [2 marks]
- same atomic number
(b) [3 marks]
- some are radioactive
13.
Owain is asked about alpha radiation in a WJEC Physics paper.
(a) [2 marks]
- stopped by paper
(b) [3 marks]
- dangerous if ingested
14.
Owain is asked about beta radiation in a WJEC Physics paper.
(a) [2 marks]
- moderately ionising
(b) [3 marks]
- neutron → proton + e⁻
15.
Owain is asked about gamma radiation in a WJEC Physics paper.
(a) [2 marks]
- weakly ionising, very penetrating
(b) [3 marks]
- stopped by thick lead / concrete
16.
Owain is asked about half-life in a WJEC Physics paper.
(a) [2 marks]
- cannot be changed
(b) [3 marks]
- used to choose a source
17.
A sample has activity 800 Bq and half-life 2 h. Activity after 6 h
[3 marks]
- Final answer: 100 Bq
18.
How many half-lives from 640 to 40 Bq
[3 marks]
- Final answer: 4
19.
Mass number of alpha decay of 238/92 U
[3 marks]
- Final answer: 234/90 Th
20.
Count rate 120 cpm, background 20. Corrected rate
[3 marks]
- Final answer: 100 cpm
21.
A source falls from 240 Bq to 30 Bq. How many half-lives?
[3 marks]
- Final answer: 3
22.
Percentage remaining after 2 half-lives
[3 marks]
- Final answer: 25%
23.
Owain carries out a WJEC-style required practical linked to atomic structure and radioactivity. This is a typical WJEC required-practical style question.
(a) [2 marks]
- Independent: the independent variable for this topic
- Dependent: the measured outcome
(b) [2 marks]
- keep all other variables constant
- so the test is fair / only one variable is changed
(c) [2 marks]
- repeat and calculate a mean / use a tighter method
24.
Owain carries out collecting valid data for atomic structure and radioactivity. This is a typical WJEC required-practical style question.
(a) [2 marks]
- Independent: a chosen factor
- Dependent: a quantitative measurement
(b) [2 marks]
- calibrated instrument
- so the test is fair / only one variable is changed
(c) [2 marks]
- systematic error from zero error
25.
Owain carries out drawing a graph for atomic structure and radioactivity. This is a typical WJEC required-practical style question.
(a) [2 marks]
- Independent: x-variable
- Dependent: y-variable
(b) [2 marks]
- same scale / same apparatus
- so the test is fair / only one variable is changed
(c) [2 marks]
- not drawing a line of best fit through the trend
26.
Owain carries out evaluating a method about atomic structure and radioactivity. This is a typical WJEC required-practical style question.
(a) [2 marks]
- Independent: method change
- Dependent: precision / accuracy
(b) [2 marks]
- same sample size
- so the test is fair / only one variable is changed
(c) [2 marks]
- too few repeats
27.
Compare the nuclear model with an isotope.
[4 marks]
- tiny positive nucleus, electrons in shells
- same protons, different neutrons
- give one linked difference
28.
Compare an isotope with alpha radiation.
[4 marks]
- same protons, different neutrons
- helium nucleus, 2+ , highly ionising, weakly penetrating
- give one linked difference
29.
Compare alpha radiation with beta radiation.
[4 marks]
- helium nucleus, 2+ , highly ionising, weakly penetrating
- fast electron, stopped by aluminium
- give one linked difference
30.
Compare beta radiation with gamma radiation.
[4 marks]
- fast electron, stopped by aluminium
- electromagnetic wave
- give one linked difference
31.
Apply your knowledge of activity to this situation: becquerel (Bq)
[3 marks]
- becquerel (Bq)
32.
Apply your knowledge of irradiation to this situation: does not make the object radioactive
[3 marks]
- does not make the object radioactive