Hi everyone, I'm having trouble understanding these questions so could someone pls explain them.
Thanks!
Hey! The first question is sort of just a by-definition one; radioactivity is when elements shed electrons/helium atoms due to an instability in the nucleus. This can occur because of three reasons; One, the ratio of neutrons to protons is too high. Two, the ratio of neutrons to protons is too low. Three, there are just too many neutrons and protons. Thus, the answer is definitely D.
Question 9 is the same; the salt bridge is literally used just to complete the circuit. Remember from like year 8 science that, if you want a circuit to work, it needs to be a complete loop. Thus, the electrons might flow one way (through the external circuit), but the 'left over' electrons/ions need some way to continue to flow. Thus, we use a salt bridge soaked in a conductive substance.
For your last question, looks like you need to do some research on radioactive isotopes. The questions you need to ask yourself are;
- Is a half life of 12 days long or short? If it is long, then you don't want it in the human body (as it will continue to damage tissue for ages!). If it is short, it is likely suitable.
- What is beta decay? Is it harmful to the human body?
- What is low energy gamma radiation? Is it harmful to the human body?
As this is only a two marker, a very brief over view of the above points is likely enough. Generally, however, isotopes used for medicine have a much shorter half-life (ie. 6 hours), and will only emit very low energies of one type of radiation. So, this substance is unlikely to be suitable for medical purposes.