The process of heating an ore strongly in the presence of excess air is called:
A. Leaching
B. Smelting
C. Roasting
D. Calcination
Answer: Option C
Solution (By JKSSB Mock Tests)
Roasting involves heating sulfide ores in excess air to convert them to oxides and remove sulfur as SO₂. Example: 2ZnS + 3O₂ → 2ZnO + 2SO₂. Calcination is heating in absence of air (for carbonates/hydroxides). Smelting is reduction. Leaching uses chemicals.
Explanation:
The Chlor-alkali process involves the electrolysis of aqueous NaCl (brine). It produces sodium hydroxide (NaOH) at the cathode, chlorine gas (Cl₂) at the anode, and hydrogen gas (H₂) at the cathode. The Solvay process produces sodium carbonate, not sodium hydroxide.
Explanation:
Fe in FeCl₃ goes from +3 to +2 in FeCl₂, gaining an electron – reduction. Sn in SnCl₂ goes from +2 to +4 in SnCl₄, losing electrons – oxidation. FeCl₃ is the oxidizing agent, SnCl₂ is the reducing agent.
Explanation:
Chlorination is the addition of chlorine gas or bleaching powder to water to disinfect it. Chlorine is a strong oxidizing agent that kills pathogenic (disease-causing) bacteria and viruses, making the water safe for drinking. It does not remove hardness or suspended impurities.
No comments yet. Be the first to start the discussion!