Hey!
This would depend on your assessment task itself. But if I were you, I would base my inquiry question on the syllabus dot points. Choosing a syllabus dot point would depend on your assessment task. If it was something to do with an experiment, I would probably do the dot-points like below:
"Conduct a chemical analysis of a common household substance for its acidity or basicity (ACSCH080), for example:
– soft drink
– wine
– juice
– medicine"
However, if it is something to do with research, where you have to go online and search up stuff, I would base my inquiry question on dot-points like below:
"Describe the importance of buffers in natural systems"
The key is to look at your assessment marking guidelines and see what kind of inquiry question would grab full marks. In fact, the marking guidelines will formulate what your final assignment should look like. Break down the assessment task marking guidelines and see what kind of inquiry question would get you good marks.
Again, this totally depends on your assessment task. The dot-point thing is really good if your assessment was a depth study where you need to choose a topic.
The internet also has a ton of articles and tips on how to make a good inquiry question, so make sure you look into that as well. A simple google search will suffice, and upon reading them will give you a good baseline to attack the question.
Hope that helps!