Strange or unusual in a way that is hard to explain.
“There's something rather peculiar sitting on my desk that I need your opinion on.”
“It has a peculiar smell that I can't quite identify.”
Since Task 8 is literally about describing an 'unusual situation,' peculiar is one of the most directly relevant words you can use, often right at the start of your response. Use it to set up the whole description, for example 'I found a rather peculiar object on my desk,' signalling to the examiner that you understand the task's theme.
Synonyms: strange, odd, curious