Question

Determine the composition of flint glass:
A.${\text{Si}}{{\text{O}}_{\text{2}}}{\text{ + N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}{\text{ + CaC}}{{\text{O}}_{\text{3}}}$
B.${\text{Si}}{{\text{O}}_{\text{2}}}{\text{ + CaC}}{{\text{O}}_{\text{3}}}{\text{ + CuS}}{{\text{O}}_{\text{4}}}$
C.${\text{Si}}{{\text{O}}_{\text{2}}}{\text{ + }}{{\text{K}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}{\text{ + CaC}}{{\text{O}}_{\text{3}}}$
D.${\text{Si}}{{\text{O}}_{\text{2}}}{\text{ + }}{{\text{K}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}{\text{ + CaC}}{{\text{O}}_{\text{3}}}{\text{ + P}}{{\text{b}}_{\text{3}}}{{\text{O}}_{\text{4}}}$

Answer 1

Flint glass is a kind of optical glass. Optical glasses are the category of glasses which have a very high quality, are transparent and homogeneous and have specific refractive properties. They are used in lenses and also in other kinds of components in optical systems. Another example of optical glass is crown glass.

Complete step by step answer:
Two examples of optical glasses are flint glass and crown glass. Out of these two, flint glass is known to be composed of potassium silicate and lead silicate or lead oxides, silica and calcium carbonate being the common components.
Let us first consider the first option. Here, the given composition is of silica $\left( {{\text{Si}}{{\text{O}}_{\text{2}}}} \right)$, soda or sodium carbonate $\left( {{\text{N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}} \right)$ and calcium carbonate $\left( {{\text{CaC}}{{\text{O}}_{\text{3}}}} \right)$. This is the composition of soda-lime glass or soda-lime-silica glass. So this cannot be the composition of flint glass. Hence, option (A) is not correct.
Now, consider the second option. Here, the given composition is of silica $\left( {{\text{Si}}{{\text{O}}_{\text{2}}}} \right)$, calcium carbonate $\left( {{\text{CaC}}{{\text{O}}_{\text{3}}}} \right)$ and copper sulphate $\left( {{\text{CuS}}{{\text{O}}_{\text{4}}}} \right)$. Hence it is not the composition of flint glass and so the option (B) is also not correct.
Now, let us consider the third option. Here the given composition is of silica $\left( {{\text{Si}}{{\text{O}}_{\text{2}}}} \right)$, potassium carbonate $\left( {{{\text{K}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}} \right)$ and calcium carbonate $\left( {{\text{CaC}}{{\text{O}}_{\text{3}}}} \right)$. This is the composition of potash glass and so it is not the composition of flint glass. So, the option (C) is also not correct.
Now let us consider the fourth and final option. Here, the given composition is of silica $\left( {{\text{Si}}{{\text{O}}_{\text{2}}}} \right)$, potassium carbonate $\left( {{{\text{K}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}} \right)$, calcium carbonate $\left( {{\text{CaC}}{{\text{O}}_{\text{3}}}} \right)$ and lead oxide $\left( {{\text{Pb}}{{\text{O}}_{\text{3}}}} \right)$. Thus, this composition matches the composition of flint glass which has been discussed above.

So, the correct option is option (D).

Note:
When flint glass is tapped with a fingernail, it will make sound like the ringing of a bell. In this way, we can tell if the glass is flint or not.