Nuclear reactions as a source of energy

4 marks · Normal

This question is about nuclear fission in uranium-235.

(a)

State the meaning of the term 'fission' as used in nuclear physics.

[1 mark]

(b)

Describe what happens when a uranium-235 nucleus absorbs a slow-moving neutron.

[2 marks]

(c)

Name the type of energy released as a direct result of the fission reaction.

[1 mark]

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(a) Splitting of a large nucleus into two smaller nuclei (and other particles).

(b) It becomes unstable and splits forming two lighter daughter nuclei, releasing energy and several (usually three) neutrons.

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Marking points

B1 (a) · 1 mark · Gives correct definition of fission (splitting of large nucleus into smaller nuclei).

B1 (b) · 1 mark · Describes absorption of neutron by uranium-235 making it unstable.

B1 (b) · 1 mark · States that the nucleus splits, releasing energy and neutrons (accept mention of daughter nuclei/products).

B1 (c) · 1 mark · States energy released is kinetic energy (of products/nuclei).

Worked solution

a) Fission is the splitting of a large nucleus into two smaller nuclei (and other particles).

b) When a uranium-235 nucleus absorbs a slow-moving neutron, it becomes unstable and splits into two lighter nuclei, releasing energy and additional free neutrons (typically three).

c) The energy released is mainly kinetic energy of the fission products (daughter nuclei and neutrons).