Q1: More than 95% of __________ is present in corrundum.

ANS:B - A1₂O₃

More than 95% of Al2O3 (aluminum oxide) is present in corundum. Corundum is a naturally occurring crystalline form of aluminum oxide with the chemical formula Al2O3. It is a very hard mineral and is commonly used as an abrasive and in the production of gemstones such as ruby and sapphire. Corundum typically consists of more than 95% aluminum oxide, with the remainder usually consisting of trace impurities. Therefore, Al2O3 is the correct answer in this context.