In a laboratory's secure cupboard are two unlabelled radioactive sources. A scientist knows that one is a beta-emitter and the other is a gamma-emitter, but is not sure which is which.

A radiation detector, a magnet, and a thin sheet of aluminium are available.

Briefly describe two different experimental tests, using this equipment, which would allow the scientist to identify which is the beta-emitter and which is the gamma-emitter.

Test 1:

• Method:
• Outcome for beta:
• Outcome for gamma:

Test 2:

• Method:
• Outcome for beta:
• Outcome for gamma:

Radioactive phosphorus-32 (${}_{15}^{32}P$) decays by emitting $\beta$-particles.

What are the values of the proton and nucleon numbers of phosphorus-32?

• proton number =
• nucleon number =

Phosphorus-32 is used in medical treatments. It decays with a half-life of 14 days.

A freshly prepared sample of phosphorus-32 has an activity of 128 units, but after being stored in a clinic, its activity is found to be 8 units.

Determine the time, in days, for which this sample has been stored.