What is the test for an alkene?

This is a fairly straightforward question which most students applying for Chemistry at university will answer fairly easily. The answer is covered in the A-Level syllabus: alkenes turn Bromine water from Orange to colourless.However, there is a lot of mechanistic detail within this fairly simple start which can illustrate well the sort of question that an interviewer may ask. Some of the knowledge is existing A-Level knowledge and some of it is first year degree level. By walking a tutee through this question it teaches the candidate not to panic when they don't know something but instead to focus on what they do know and how it can be applied.