Question

The earthy impurities present in metals are called:
A. flux
B. slag
C. gangue
D. refractory material

Answer 1

These are the impurities that are present in the ores, for example, sand rocks. The process of separating these impurities from the ore is called mineral processing. It is an important aspect in the field of mining.

Complete answer:
Flux is any substance introduced within the smelting of ores to push fluidity and to get rid of impurities within the kind of slag.
$Gangue+flux=slag$
Nature of flux depends upon the character of gangue material. If the gangue material is acidic and basic flux is employed. Ex-
$Si{{O}_{2}}+CaO->CaSi{{O}_{3}}$
If the gangue material is basic than acidic flux is employed. Ex-
$FeO+Si{{O}_{2}}->FeSi{{O}_{3}}$
Sometimes neutral flux is employed to lower the temperature of the ore. In electroreduction of Na from NaCl.
Slag could be a by-product formed in smelting, welding, and other metallurgical and combustion processes from impurities within the metals or ores being treated. Slag floats on the surface of the molten metal, protecting it from the oxidation by the atmosphere and keeping it clean.
In mining, gangue is that the commercially worthless material that surrounds, or is closely mixed with, a wanted mineral during a ore deposit. it's a necessary, and infrequently significant, aspect of mining. It may be a sophisticated process, betting on the character of the minerals involved in it.
Refractories are materials that are immune to extreme temperature, used predominantly as furnace linings for elevated temperature materials processing and other applications during which thermomechanical properties are critical. Now let's come to the solution .

So from the above explanation the correct answer will be gangue which is option C.

Note:
Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of the metallic elements, their inter-metallic compounds, and their mixtures, which are called alloys. Metallurgy encompasses both the science and the technology of the metals.