Question

Which of the following is slag?
(A) $CaO$
(B) $CaS{{O}_{4}}$
(C) $CaSi{{O}_{3}}$
(D) $Si{{O}_{2}}$

Answer 1

Hint: When a metal is separated from its ore, the product left behind is called slag. It is actually the impurities that combine with flux to form slag. This process can be smelting or any other metallurgical process. The slag thus formed is a mixture of metal oxide and silicon dioxide. It occurs as a molten liquid. After cooling, the slag solidifies. Slag contains a high amount of iron. This is the reason why slag gets stuck to the magnet.

Complete Step by Step Answer:
Slag is the silicate of calcium, magnesium, iron, manganese, aluminium, etc. $CaSi{{O}_{3}}$ is the only compound among the given compounds which is a combination of metal oxides, that is, calcium oxide and silicon dioxide. Hence, $CaSi{{O}_{3}}$ is the slag.

Slag prevents the metal from coming into contact with the atmosphere so that it does not get oxidised. It floats on the surface of metal, that is, it is insoluble in molten metal. In some cases, the slag is a more valuable product than the metal obtained from the ore.

Flux is of two types: Acidic flux and basic flux. The acidic flux combines with basic impurity, and the basic flux combines with acidic impurity to form slag. The slag can be used for the construction of roads, the manufacturing of cement, or plant fertilisers.
Correct Option: (C) $CaSi{{O}_{3}}$.

Note: The other compounds are not a combination of metal oxide and sulphur dioxide. $CaO$ is a metal oxide. $CaS{{O}_{4}}$ is a sulphate compound. $Si{{O}_{2}}$ is sulphur dioxide.