Hi Azim I am not familiar with this paper however from experience of doing my RS paper and many other exams I would suggest this:
I looked at your paper and saw that you need to answer 4 questions which are all equally weighted. Therefore if as you have 1hour and 30 minutes you need to spend approximately 22.5 minutes on each section. So aim for 20 minutes so you will have time to check each section afterwards.
Another guidline is that it's pretty much a minute a mark! So for the eight mark questions aim to answer it in eight minutes.