(a) State two; (i) differences between nuclear fusion and nuclear fission; (ii) peaceful uses of atomic energy (b)(i) Explain chain reaction (ii) State (I) ...

Answer Details

(a)(i) Two differences between nuclear fusion and nuclear fission:

(a)(ii) Two peaceful uses of atomic energy:

• Generation of electricity in nuclear power stations.
• Production of radioisotopes used in medicine (radiotherapy) and in agriculture/industry (tracers).

(b)(i) Chain reaction: a self-sustaining nuclear reaction in which the neutrons released by the fission of one nucleus go on to cause the fission of further nuclei, each of which releases still more neutrons, so that the process continues on its own.

(b)(ii)(I) A necessary condition: there must be at least a critical mass of the fissile material present.

(b)(ii)(II) Two control components in a nuclear reactor: control rods (of boron or cadmium) that absorb excess neutrons, and a moderator (such as graphite or heavy water) that slows down the neutrons.

(c)(i) The reaction \( {}^{2}_{1}\text{H} + {}^{3}_{1}\text{H} \rightarrow {}^{4}_{2}\text{He} + {}^{1}_{0}n + \text{energy} \) is a nuclear fusion reaction (light nuclei combining).

(c)(ii) Decay constant: \[ \lambda = \dfrac{0.693}{t_{1/2}} = \dfrac{0.693}{5.40 \times 10^{3}} = 1.28 \times 10^{-4}\,\text{s}^{-1}. \]