Complex sentence: He is the first student ever to attain this perfect score in JEE-Main, an examination that is considered the "one of the toughest exams in the world" and that was termed the "mother of all exams" by New York Times.
Split into simpler sentences: He is the first student ever to attain this perfect score in JEE-Main. This exam has been termed the "Mother of all exams" and "one of the toughest exams in the world" by New York Times.