Electrostatic precipitators are suitable for removing (i). Fly ash from coal combustion (ii). Cement dust (iii). Sulfur dioxide gas
- AOnly (i)
- B(i) and (ii)Correct
- C(ii) and (iii)
- D(i), (ii) and (iii)
Solution
Concept
ESP removes particulate matter, not gaseous pollutants.
Step-by-step solution
1. ESP charges particles and collects them on plates. 2. Fly ash is a particulate, so ESP is suitable. 3. Cement dust is a particulate, so ESP is suitable. 4. SO2 is a gas, so ESP cannot remove it (use a scrubber). 5. So (i) and (ii) are correct.
Explanation
An ESP works on particles by giving them an electric charge. Fly ash and cement dust are particles, so ESP works well. Sulfur dioxide is a gas and needs a scrubber or absorption unit.
Why the other options are wrong
A: Cement dust is also removed. C and D: SO2 gas is not removed by ESP.
Shortcut
ESP = particles only. Gases need scrubbers.
Common mistake
Thinking ESP removes all pollutants including gases.
Correct answer: B) (i) and (ii)