Gamma radiation is used to sterilise medical equipment sealed in plastic packaging. (a) State one property of gamma radiation that allows it to sterilise eq...

(a) The key property is that gamma radiation is very penetrating and can pass through the plastic packaging to reach the medical equipment inside. [1] This means the equipment can be sealed first (maintaining sterility) and then exposed to gamma rays that kill bacteria and other microorganisms on the instruments without needing to open the packaging.

(b) Alpha radiation would not be suitable because:

1. Alpha particles are stopped by a thin sheet of paper or plastic. [1] They have very low penetrating power due to their large mass (4 u) and high charge (+2), which causes them to interact strongly with matter and lose energy quickly.
2. Because of this, alpha radiation would not reach the equipment inside the sealed plastic packaging. [1] The packaging itself would absorb all of the alpha particles before they could sterilise anything.

(c) The gamma source should have a long half-life because:

1. The source must last a long time without needing to be replaced. [1] A sterilisation facility processes equipment continuously over months or years, so a source that decays quickly would be impractical and costly to replace.
2. A short half-life would mean the activity drops quickly, causing the source to become too weak to sterilise effectively in a short time. [1] With a long half-life, the activity remains high enough for reliable sterilisation over an extended period.