A level: Radioactivity Questions

Q20. An isotope of potassium is used to date rocks.

(a) The isotope decays into an isotope of argon (Ar) mainly by electron capture.

The decay is represented by this equation:

(i) Complete the equation to show the decay by filling in the gaps.

[2 marks]

(ii) Explain which fundamental interaction is responsible for the decay.

[2 marks]

(b) One decay mechanism for the decay of results in the argon nucleus having an excess energy of 1.46 MeV.

It loses this energy by emitting a single gamma photon.

Calculate the wavelength of the photon released by the argon nucleus.

[3 marks]

calcium-40 nuclide - .

Suggest how the emissions from a nucleus of decaying potassium can be used to confirm which decay process is occurring.

[3 marks]

(Total 10 marks)