Hello,
The number of questions in a CEM 11+ Test (as Redbridge) changes year to year and so it is impossible to answer your question.
If you need more details about this exam, I would suggest that you look online at:
https://www.redbridge.gov.uk/media/5945/2020-information-guidance-for-11plus-parents.pdf
and the Familiarisation Booklet: https://www.redbridge.gov.uk/media/6497/familiarisation-booklet-for-2020-entry.pdf