The impurities present in an ore are known as: MCQ with Answer and Explanation

The impurities present in an ore are known as:
A. Slag
B. Flux
C. Gangue
D. Matrix
Answer: Option C
Solution (By JKSSB Mock Tests)
The unwanted earthy or sandy impurities present in an ore are called gangue (or matrix). Flux is added during smelting to react with these impurities, and the resulting fused mass is called slag, which is lighter and floats on top of the molten metal for easy removal.

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Practice More chemistry Questions

Question #1
The process of converting a concentrated ore into its oxide by heating in excess air is:
A. Calcination
B. Smelting
C. Roasting
D. Refining

Correct Answer: Option C


Explanation:
Roasting is the process of heating the concentrated ore (usually sulfide ores) strongly in the presence of excess air below its melting point. It converts the ore to its oxide form and removes volatile impurities as gases (e.g., 2ZnS + 3O₂ → 2ZnO + 2SO₂).

This question belongs to: Science chemistry
Question #2
The process of separating ammonium chloride from a mixture of ammonium chloride and salt uses:
A. Sublimation
B. Filtration
C. Evaporation
D. Distillation

Correct Answer: Option A


Explanation:
Ammonium chloride sublimes on heating; it converts directly from solid to vapor, leaving behind common salt. The vapors can be condensed on a cold surface to obtain solid NH₄Cl. This method works for any mixture where one component sublimes and the other does not.

This question belongs to: Science chemistry
Question #3
Chlorine used in water purification acts by:
A. Dissolving salts
B. Adding flavor
C. Killing microorganisms by oxidation
D. Removing suspended particles

Correct Answer: Option C


Explanation:
Chlorine forms hypochlorous acid (HOCl) which is a strong oxidizing agent that destroys bacteria and viruses. It does not remove particles (filtration does) or dissolved salts.

This question belongs to: Science chemistry