As Mattydo says, during the OPC assessments you will rarely complete everything in front of you and they do this to put you under pressure.
However, you should really finish all 25 questions well within 70 minutes. 2.5 mins per question is a long time and these type of questions are not meant to be pondered and thought over.
You should give the first answer you think is right, do a quick double check and move on. Overthinking these questionnaires is a killer.
Not much help to you now but I’ve found the best tactic is to select the obvious 1st choice and last choice first and then decide on 2nd and 3rd answers last.
Best of luck with your result!