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A level: Radioactivity Questions

Q15.

(a) Calculate the radius of the nucleus.

r0 = 1.3 × 10–15 m

(2 marks)

(b) At a distance of 30 mm from a point source of γ rays the corrected count rate is C.

Calculate the distance from the source at which the corrected count rate is 0.10 C, assuming that there is no absorption.

(2 marks)

(c) The activity of a source of β particles falls to 85% of its initial value in 52 s.

Calculate the decay constant of the source.

(3 marks)

(d) Explain why the isotope of technetium, Tc 99m, is often chosen as a suitable source of radiation for use in medical diagnosis.

(3 marks)

(Total 10 marks)