Hi Rajan!
Ideally you should know the mechanism as it gives you an understanding of what occurs in a reaction and what are the intermediates that are formed. Otherwise, you will have to memorize every reaction w/o understanding the logic, which is detrimental.
Hope this answers your question!
Arika (State Head @ Careers360)
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile