1000+ Chemistry MCQ with Answers Pdf - 2

Question: 6

What is meant by quenching?

Mild steel is heated to red hot temperature and then cooled suddenly by plunging into oil or cold water. This process is called quenching. This makes steel very hard and brittle.

Question: 7

What is smelting?

The high temperature reduction process in which the metal is usually obtained in a molten state is called smelting. It is carried out in the presence of a flux.

Question: 8

What is roasting?

The process of heating the concentrated ore in the presence of excess of air is called roasting. Usually sulphide ores are subjected to roasting to give oxide.

Question: 9

What is calcination?

The process of heating the concentrated ore in the absence of air at a temperature sufficient to melt the ore is called calcination.

During this process, the moisture and volatile impurities are removed and the carbonate ores may also be decomposed.

Question: 10

Why is sulphuric acid called King of chemicals?

Sulphuric acid, is the most important chemical, used in the manufacture of large number of substances. Hence it is called as King of chemicals.