This document is a study sheet from Gokul Academy of Science in Nagpur, India for class 12 students. It contains review questions in Biology, Chemistry, Physics, and Mathematics. In Biology, questions cover selective reabsorption and kidney stones. Chemistry questions address preparing phenol from aniline and the reaction of phenol with bromine and bromine water. Physics asks about deriving the expression for variation of gravity with altitude. Mathematics questions prove trigonometric identities.