57. Quartz is made of A.Calcium Sulphate B.Calcium Silicate C.Sodium Sulphate D.Sodium Silicate
Answer: Option D Solution: Quartz is an abundant mineral in the Earth’s continental crust. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz, several of which are semiprecious gemstones. Most quartz used in microelectronics is produced synthetically. Large, flawless and un-twinned crystals are produced in an autoclave via the hydrothermal process. The process involves treating crushed natural quartz with hot aqueous solution of a base such as sodium hydroxide.
