Question

Which one of the following is not used as a raw material in the manufacture of glass?
1. Soda
2. Alumina
3. Borax
4. Gypsum

Answer 1

Correct Answer - Option 4 : Gypsum

The correct answer is gypsum.

• Glass is formed when molten material is cooled so quickly that its constituent atoms do not have time to align themselves into an ordered lattice. 
• Soda ash varies in density, size, and shape when mined and processed. 
  • This flexibility allows it to be used in a variety of everyday products like glass. 
  • Specifically, soda ash is used to make the most common type of glass, soda-lime silica glass.
  • It is used as the main ingredient because soda ash naturally reduces melting temperatures and its alkali effectively supports the shaping of the glass item. 
• Alumina is used in glassmaking because of its superior mechanical and optical properties. 
  • Alumina can form glass if it is alloyed with calcium or rare-earth oxides.
  • But the required quenching rate can be as high as 1000 degrees per second, which makes it difficult to produce bulk quantities.
• Glass manufacturers add borax to the silica base to:
  • significantly lower melting temperature and viscosity, inhibit crystallization of the glass, control thermal expansion, and inhibit devitrification.
  • The resulting products have inherent durability and chemical resistance and are tough enough to withstand considerable mechanical or thermal shock.