During rape on a virgin, rupture of hymen occurs at the following degree:

Tearing of hymen in a virgin during rape usually occurs posteriorly at the sides, in the 4 or 8 O'clock position, or in the middle line of the hymen. More than two tears are unusual. Tears usually occur in the posterior midline of the hymen because the hymen lies suspended across a potential space, whereas anteriorly the periurethral tissues buttress the hymen. Ref: The Essentials of Forensic Medicine and Toxicology by K S Narayan Reddy, 27th edition, Page 356.