Two models both explain the red-shifts measured from distant galaxies. Only model P predicts a background of cooled radiation from a hot early Universe.
Such a background is then detected independently by several groups.
Which conclusion is best supported?
Both models are ruled out because the radiation is now cool.
Model Q is favoured because red-shift excludes a hot beginning.
Both models are equally supported because both explain red-shift.
Model P is favoured because it explains both observations.
94 exam-style questions on Edexcel GCSE Physics 7.2 The Universe and red-shift, covering 7.2.1 Big Bang and Steady State theories, 7.2.2 Evidence for the Big Bang, 7.2.3 The Doppler effect and red-shift, 7.2.4 Red-shift as evidence for an expanding Universe, and 7.2.5 The CMB and the accepted model. Each one has a worked solution and a mark scheme showing where the marks go.