Question

The acidic refractory material is:
(A) \[CaO\]
(B) \[{P_2}{O_5}\]
(C) \[Si{O_2}\]
(D) \[MgO\]

Answer 1

Hint: Refractory material refers to a substance that is resistant to heat. There are two types of refractory materials, refractory metals and their alloys, and non-metallic refractory materials, which are usually made of elements, such as oxygen, carbon, nitrogen, silicon, etc.

Complete step-by-step solution:
A refractory material is one that retains its strength at high temperatures and corrosive environments. Refractories are inorganic, porous, non-metallic and heterogeneous materials. High resistance to thermal creep deformation, high strength, thermal stability, and high resistance to acidic or alkaline environments, are defining characteristics of most refractory materials.
The mineral-based refractories are some naturally-occurring minerals that are refined and treated to give them their properties. Oxides and dioxides of calcium, aluminum, sodium, magnesium, and silicon are mostly referred to. These are the most affordable refractories, used in industry, home and light commercial use.
There are three types of refractory materials:
Acid refractories are those which are not affected by acidic substances, but easily attacked by alkalis. These are used in areas where the atmosphere is acidic. Acid refractories such as zirconia (\[Zr{O_2}\]), alumina (\[A{l_2}{O_3}\]), silica (\[Si{O_2}\]) refractories.
Neutral refractories are chemically stable towards both acids and alkalis and are used in areas where the atmosphere is either acidic or basic. The common substances of neutral refractories are Carbon, Chromites (\[C{r_2}{O_3}\]) and Alumina (\[A{l_2}{O_3}\]).
Basic refractories are those which are attacked by acids but are stable to alkaline substances. These are used in areas where the atmosphere is basic. Since these do not react with alkalis, they are important for furnace linings where the environment is alkaline; for example non-ferrous metallurgical operations. The common substances of basic refractories include magnesia (MgO), chrome-magnesia and dolomite.

Hence, the correct option is (C).

Note: We concluded that the raw material of acidic refractory is silica having \[Si{O_2}\] content more than \[93\% \]. Refractory materials have high melting points and on that basis they are again classified into three classes- normal, average and super.