Question

Certain statements regarding different varieties of glass are given below.
(a) Addition of boron trioxide to the ingredient of glass makes it thermal resistant.
(b) Addition of some transition metal oxides imparts colour to the glass.
(c) Lead oxide is added to the ingredients of the glass to make it impact resistant.
(d) Addition of cerium oxide to glass makes it photochromatic.
Which of the following options is correct regarding the above statements?

• A. a and b
• B. c and d
• C. a, b and c
• D. only d

Answer 1

Answer: (A)

a and b

Addition of boron trioxide or boric acid to the ingredient of glass makes it thermal resistant. Addition of some transition metal oxides imparts colour to the glass for example the purple-blue colour of cobalt, the chrome green or yellow of chromium, and the violet of manganese. The addition of lead oxide to glass raises its refractive index and lowers its working temperature and viscosity. It is desirable owing to its decorative properties. Cerium oxide is used in ceramics, to sensitize photosensitive glass. It absorbs ultraviolet radiation strongly,