Hello aspirant

You can give exam for only Chemistry, next year your marks will be accepted even if you don't repeat all the subjects. If you go for class improvement for all subjects you will have to appear for all practicals assignments and even graded subjects again.

So don't worry in both cases your marksheet will be accepted for Engineering . But the thing is you should fulfill the eligibility criteria for Engineering ie minimum 50% marks in PCM and appear for CET or JEE main.