POLYMORPHOUS

Polymorphous: 

a single substance whitch crystalline in two or more forms under different cinditions of solidification is called polymorphous and phenomenon is polymorphism. These polymorphic forms are also called allotropic forms or allotropes. ‘

e.g. Carbon exists as diamond and graphite

           Sulphur exists as rhombic and monoclinic.

Glass is a homogeneous mixture ofSiOz, NaIO, boron oxide (B203) and transition metaloxide to impart colour.

                       It is optically transparent material.
                      About 800 ditlerent types of glasses are manufactured by changing the composition. Quartz glass is obtained only from SIO2
Pyrex glass is obtained by fusing together 60-80% SiO2, 10-25% B2O3 and remaining amount of AL2O3. Glass is amorphous solid is considered as a super cooled liquid.

Sodalime glass : 75% SiOz, 15% N320 and 10% C30

Red glass : SiO2 and trace amount of gold & copper.

Yellow glass : SiO2 + U02

Blue glass : SiOz + CaO or CuO

Green glass : SiO2 + FeZO3 or CuO