Sabbatical from job for studying

While going for higher studies is the prerogative of an individual, it is his/her responsibility to inform the Employer and obtain their permission as per the HR norms of the Company one was appointed in the first place. Therefore, advise your friend to approach the HR of his/her employer and get clarification and act accordingly.

It is policy of employer to decide whether to grant sabbatical or not, however, no such facility can be claimed.. 

In general, a leave is sanctioned only for the reasons agreed in writing in the form of rules and regulations.   There is no mention of such sabbatical leave for preparing for competitive examinations unless such examination is concerned with the working of the institution (internal).  However first the matter should be discussed with sanctioning authority, and facts should be stated in the leave letter.

Yes, sabbatical, in the sense the word is understood in the ordinary sense implies taking a break from the routine duties in order to acquire new skills or enhance knowledge. In that sense, preparing for studying for competitive examination is outside the scope of the term.