.
- In the calculation of the energy released in the reaction, some candidates made themselves creditably equal to the required task. However, few candidates found the conversion of the unified atomic mass to kilogram difficult.
- Very few candidates did the correct thing while most of other respondent candidates derailed by starting their responses on a wrong note; i.e with wrong formula. Generally, performance was fair.
The expected responses are:
(a)(i) Radioactivity is the decay/disintegration of the nucleus of an unstable
nucleus/atom (of an element) with the release of any one, two or all of
alpha, beta and gamma radiations.
(ii) Types of radioactivity
(b)(i) Advantages of nuclear fusion over nuclear fission
e.g
- greater energy is released
- less dangerous radiations are released
- raw materials required are cheaper
- raw materials are readily available.
(ii) Methods of detecting radioactivity
Any correct 2
e.g
- photographic films
- Geiger muller (G-M) tube
- (Electron) – e loud chamber
- semiconductor detectors
(c) m = mass defect = (mass of products ) – (mass of reactants)
= 4.00150 2.00141
+ 1.00728 - + 3.00160
5.00878 5.00301
Mass defect = 0.00577u
= 5.77 x 10-3u
= 5.77 x 10-3 x 1.7 x 10-27 kg
= 9.81 x 10-30 kg
E = mc2
= 9.81 x 10-3 x ( 3 x 108 )2
= 8.83 x 10-13 J
(d) λ = h
mV = 6.6 x 10-34
9.1 x 10-31 x 4.8 x 108
= 1.51 x 10-12 m
