Basically Whatsapp isn't a distraction,  the people you chat with and spend time with are. So what you can do is either make use of some apps available which help you to access certain other apps for certain period of time only after which whatsapp automatically gets locked after the allotted time. This can be one of the solutions. The second and the best one can be is to make your mind realize that your goal iss much more important than all these distractions. Once you achieve your goal, complete your exams, you will surely get time to spend with all your friends. Mute all the notifications first of all. And keep studying maximum time and control yourself and only when you get frustrated and need some time off from studies, use the whatsapp that too for a limited time. Thank you.

Hello there,
You need to control yourself from using WhatsApp for a long time. Check the important messages and keep your phone aside. Try concentrating in your work. Whenever a notification comes, don't run after that. You should concentrate in your studies, and after an hour you can check your WhatsApp for few minutes. Try to remain only in those WhatsApp groups which are important, related to your studies or work. Exit from the unnecessary groups which send messages a lot.
Hope this answer helps you.
Good luck!!