An underground oil pipeline is buried under a layer of soil. A technician needs to locate a leak in this pipeline. A small amount of a radioactive tracer isotope is dissolved in the oil, so that oil leaking from the pipe carries the tracer into the surrounding ground.
The technician uses a radiation detector above the ground surface to search for the leak by looking for an area where the count rate is significantly higher than the background rate.
(i) State and explain the type of radiation (α\alphaα, β\betaβ, or γ\gammaγ) that must be emitted by the tracer isotope for the leak to be detected from above the ground.
(ii) The half-life of the tracer isotope is 6.0 hours6.0\text{ hours}6.0 hours. Explain why an isotope with a half-life of this duration is suitable.
Cobalt-59 is a stable isotope of the element cobalt, while cobalt-60 is a radioactive isotope. A nucleus of cobalt-59 contains 32 neutrons, and a nucleus of cobalt-60 contains 33 neutrons.
Determine how the number of protons, neutrons, nucleons, and electrons in a neutral atom of cobalt-59 compares with those in a neutral atom of cobalt-60. Fill in the comparative relationship for each particle as one of the following:
| Particle in a neutral atom of cobalt-59 | Comparative relationship |
|---|---|
| Number of protons | |
| Number of neutrons | |
| Number of nucleons | |
| Number of electrons |
484 exam-style questions on CIE IGCSE Physics 5.2 Radioactivity, covering 5.2.1 Background radiation and measuring count rate, 5.2.2a Alpha, beta and gamma emission, 5.2.2b Deflection and ionising effects of nuclear radiation, 5.2.3a Radioactive decay, 5.2.3b Effects of decay on the nucleus and decay equations, 5.2.4a Half-life, 5.2.4b Choosing isotopes for applications, and 5.2.5 Effects of ionising radiation and safety precautions. Each one has a worked solution and a mark scheme showing where the marks go.