NDA General Science Chemistry Questions Part 2

Soda Lime Glass: Hard glass contains potassium instead of sodium, has a higher melting point, and greater resistance to reagents and as such it is more suitable for chemical apparatus. Flint glass is potash-lead glass having a high refractive index and, therefore, suitable for optical purposes.
Pyrex Glass: Pyrex glass or borosilicate was created with the addition of boron to the mixture. Pyrex is more resistant to heat as the thermal expansion coefficient of Pyrex is about one-third of soda-lime silica glass. It also has high durability against chemicals. Pyrex is also lighter in weight. Pyrex-Wafers are an ideal solution for anodic bonding processes, as the thermal coefficient of expansion almost perfectly matches that of silicon. Apart from this, pyrex also has good acid resistance and a high optical transmission over a wide wavelength range.It can be ground, polished, and coated according to customer-specific requirements