CAIE IGCSE Physics Nuclear Fission and Fusion

Practise distinguishing fission from fusion, completing nuclide equations and explaining how a small decrease in total nuclear mass corresponds to energy release.

Exam points

describe fission as neutron-triggered splitting of a heavy nucleus into smaller nuclei and neutrons
describe fusion as joining light nuclei into a heavier nucleus, as in hydrogen reactions in stars
balance A and Z in nuclide equations and link lower product mass qualitatively to released energy

[Maximum number: 3]

The isotope uranium-235 is represented by

{ }_{92}^{235} \cup .

(a)

Uranium-235 is a fuel used in nuclear reactors.

[ 3 ]

(i)

State the process by which energy is released from uranium-235 in a nuclear reactor.

[ 1 ]

(ii)

A nuclide equation for this process is

{ }_{92}^{235} \mathrm{U}+{ }_{0}^{1} \mathrm{n} \rightarrow{ }_{54}^{140} \mathrm{Xe}+{ }_{38}^{94} \mathrm{Sr}+2{ }_{0}^{1} \mathrm{n} .

Describe the mass and energy changes that take place during this process in a nuclear reactor.

[ 2 ]

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5.1.2.6—Processes of nuclear fission and question 1

Question (a)

Question (i)

Question (ii)