A focused three-component revision and exam practice pack for SP6g, covering the complete Edexcel Separate Science Physics specification for activity, the becquerel, half-life definition and calculations (P6.23–P6.27).

Topic Mastery Sheet covers the definition of activity (decays per second, unit Bq) and why activity always decreases over time; the two equivalent definitions of half-life (time for activity to halve; time for half the undecayed nuclei to decay); the explanation of why half-life is statistically reliable despite individual decay being random; three calculation methods - counting half-lives from a fraction, reading from an activity-time graph, and using the formula fraction = 0.5ⁿ; and a table matching isotopes to appropriate applications by half-life. The 0.05 g → 0.0125 g in 12 hours calculation and the fraction for n = 4 are worked through in detail as these appear directly in the Higher mark scheme.

Student Exam Practice Sheet includes a graph-based half-life determination (3.5 years); the 0.05 g / 12 hours mass calculation requiring students to identify the number of half-lives; and the fraction = 0.5⁴ calculation. Question format matches the Edexcel test style.

Teacher Answer Key provides a complete mark scheme specifying the three-step method for the mass calculation (fraction → number of half-lives → half-life value + unit) and that the unit “hours” is required for the third mark.

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