. This is not a popular question, most candidates could not profer correct reason why
uranium is not the only useable element for nuclear fission reaction.
Most candidates who attempted part (b) were able to complete the table correctly however, the plotting of the graph was poorly done as choice of scales was a problem. Few could not read-off the count rate at 12 years. Most candidates were able to mention Geiger – Muller counter as detector.
Part(c) this simple problem on energy quantization was poorly attempted some candidates could not achieve the necessary conversion and some made use of wrong formula.
The expected answer are:
. (a) Yes, Uranium is used because it is heavy and unstable. Elements with similar properties
can also be used.
b(i)
t/years |
0 |
5 |
10 |
15 |
20 |
Connote rate min-1 |
4000 |
2000 |
1000 |
500 |
250 |
(ii)
Both axes distinguished
Reasonable scales (both axes)
Five points correctly plotted
Smooth curve
(iii) Count rate at 12 years
Correctly shown on graph
Correctly read
(iv) Suitable detectors
- Scintillating detector
- Geiger Muller Tube
- Photographic films
- Electron cloud chambers
C (i) Transition C
This transition will produce the highest energy
(ii) E =
l = = 6.6 x 10-34 x 3 x 108
9.8 x 1.6 x 10-19
= 1.3 x 10-7m