Sand or silicon dioxide - It is a naturally occurring mineral and in its purified form it is used as a raw material in cement and glass.
Sodium silicate - It is a compound of silicon and is commonly used in the preservation of eggs, as it helps in increasing shelf life of eggs
Ferrosilicon - It is an alloy of Iron and Silicon and very hard and tough steel . Silicon Carbide is a compound of silicon and is very hard hence used as a grinding wheel.
Silicone - It is a polymer formed by the backbone of chain of silicon-oxygen. They are rubber-like substances and used in cooking utensils , thermal insulation etc.