Correct option is D
1.
(A) Aqueous solutions of sodium and ammonia:
Aqueous solutions of sodium and ammonia are used for desulfurization processes in thermal power plants. These react with SO₂ to form neutral or less harmful compounds.
Correct Statement.
2.
(B) Liquid nitrogen:
Liquid nitrogen has no role in controlling SO₂ emissions. It is mainly used in cryogenic processes for other industrial applications.
Incorrect Statement.
3.
(C) Aqueous solutions of calcium and magnesium:
Calcium and magnesium-based solutions, such as lime or limestone slurries, are commonly used in flue gas desulfurization systems to absorb and neutralize SO₂ emissions.
Correct Statement.
4.
(D) Chlorine:
Chlorine is not used for controlling SO₂ emissions. It is used for disinfection in water treatment processes.
Incorrect Statement.
Hence, the correct options are
(A) and (C).
Information Booster: 1. Flue Gas Desulfurization (FGD):
· Removes sulfur dioxide (SO₂) from exhaust gases using sorbents like lime or limestone.
· Forms products like calcium sulfite or calcium sulfate (gypsum).
2. Role of Sodium and Ammonia:
· Sodium hydroxide reacts with SO₂ to form sodium bisulfite and sodium sulfite.
· Ammonia forms ammonium sulfate, which is often used as a fertilizer.
3. Importance of Controlling SO₂:
· Prevents acid rain formation.
· Reduces health risks like respiratory issues.
4. Alternative SO₂ Control Methods:
· Dry scrubbing systems.
· Using activated carbon.
· Pre-combustion desulfurization techniques.
Additional Knowledge: · Liquid Nitrogen:
· Used for cryogenic applications like rapid freezing or cooling. Not applicable for SO₂ control.
· Calcium and Magnesium Compounds:
· Used in wet and dry scrubbers for SO₂ absorption. These compounds form harmless salts.
· Chlorine:
· Widely used in water treatment plants for disinfection but irrelevant to SO₂ mitigation.
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