Q1: Which of the following is a synthetic abrasive ?

ANS:D - Silicon carbide

Among the options provided, Silicon carbide is a synthetic abrasive. Here's a brief explanation of each:

1. Corundum: Corundum is a natural abrasive mineral that consists of aluminum oxide (Al2O3). It is commonly found in nature as rubies and sapphires and is used as an abrasive in various forms such as aluminum oxide abrasives.
2. Emery: Emery is a natural abrasive that consists of a mixture of corundum and magnetite (iron oxide). It is typically found as granular or powdered material and is used in abrasive applications.
3. Pumice: Pumice is a volcanic rock that forms when lava with high water and gas content erupts from a volcano. It is a natural abrasive that is commonly used for polishing, smoothing, and exfoliating.
4. Silicon carbide: Silicon carbide is a synthetic abrasive material that is produced by heating a mixture of silicon and carbon at high temperatures. It is extremely hard and is used in abrasive applications such as grinding, cutting, and sanding. Silicon carbide abrasives are available in various forms, including bonded abrasives, coated abrasives, and abrasive powders.