(a)[1]
The uranium isotope that occurs most abundantly in nature is uranium-238 ($^{238}_{92}\text{U}$). State how a neutral atom of uranium-235 differs from a neutral atom of uranium-238.
(b(i))[1]
Inside the reactor of a nuclear power station, a uranium-235 nucleus absorbs a slow-moving neutron and undergoes fission. State what happens to the nucleus of an atom during fission.
(b(ii))[4]
Explain how fission can produce a chain reaction in the reactor.
(b(iii))[1]
State the purpose of the moderator in the reactor.
(b(iv))[2]
Explain what the control rods do in the reactor.