These are similar to one and two mark questions but you will be expected to write in more depth for three and four mark questions.
The answers here give lists of valid points that could be included in your answer.
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What is the charge on the helium atom in the figure?
Explain your answer. [3 marks]
It is neutral  because protons have positive charge and electrons have negative charge  and there are equal numbers of protons and electrons .
The three marks indicate that more detail is needed than just stating the overall charge or the numbers of particles. Both the numbers of particles and their charges should be included.
Technetium-99 used in hospitals emits gamma radiation and has a half-life of 6 hours.
After treatment, hospital equipment may become contaminated.
Describe the level of the hazard associated with contamination with technetium-99.
You should include in your answer a description of how the level of hazard changes over time. [3 marks]
Initially there is a high level of hazard (activity initially high) . The level of hazard drops to a low level quickly (drops to safe level quickly)  due to short half-life .
It is important in this question to recognise that 6 hours is a relatively short half-life. Some radioisotopes have a half-life of millions of years.
Transmutation is the name given to a process where one element changes into another.
Explain and compare how two different types of radioactive decay can cause transmutation. [4 marks]
In alpha decay, two protons and two neutrons are emitted from the nucleus as an alpha particle meaning the atomic number decreases by two . In beta decay, a neutron turns into a proton and emits an electron meaning the atomic number increases by one . In both cases the proton number has changed  meaning a new element is formed .
This could be summarised by the following list: