if you block whatsapp, they can use telegram.
if they block facebook, they can use an alternative.
if the whole idea is to block resources to communicate with someone outside the exam center, they would need to block access to the entire internet because there are infinite ways of connecting with each other out there.
the main problem here is that... this is not a national security issue. this is not even an issue of public safety. this is just idiocy and shows the incompetence of the state administration.