Most of the questions which are asked in Chemistry are directly from NCERT or are based on it. If you have practiced NCERT thoroughly including its exercises, in-text questions then there is a huge chance that you will easily score above 90 marks. Moreover time is also not a constraint in Chemistry paper as you will have plenty of time if you write the answers precisely and to the point.
Focus on reasoning type questions and practice all structures. It will help for sure.
If you know the concepts and have learned most of the ‘ratta’ part by heart, then you should give less time to Chemistry preparation as compared to Physics or Maths.
Be confident about your preparation and fear nothing.