Yes there are questions related to chemical reactions in JEE Exam. 

To practice them a student must have NCERT textbook of 11th and 12th standard of Chemistry. Also chemical reactions can be studied from reference books.

To get thorough with reactions write each reaction at least 5-10 times everyday. Now there are very basic reactions which are easy but don't avoid them as they are useful when product is asked for complicated reactions.

Practice multiple choice questions everyday based on the reactions you do.

In this way a student can get thorough with reactions.

If you still have any queries feel free to ask in the comment section down below.