Observe the given figure and answer the following questions:
Identify the statements which hold true for the figure 'X'.
A. Dirty air is entering through G and leaving through I.
B. It can remove 99 percent of the particulate matter from the power plant exhaust.
C. It can remove very small particulate matter.
D. Sulphur dioxide can be removed by this.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A and D only
A. Dirty air is entering through G and leaving through I. — True. In the scrubber, dirty air enters at G and clean air leaves at I.
B. It can remove 99 percent of the particulate matter from the power plant exhaust. — False. This is the electrostatic precipitator, not the scrubber.
C. It can remove very small particulate matter. — False. A scrubber removes gases; very small particles are not removed even by precipitators.
D. Sulphur dioxide can be removed by this. — True.
Note: This question is from Chapter 16, Environmental Issues, of the pre-rationalised NCERT book. This chapter is not in the present NCERT book (2026-27). The extract below is from the pre-rationalised edition.
NCERT Extract (Pre-rationalised edition, Chapter 16, Environmental Issues):
Air Pollution and Its Control – “… There are several ways of removing particulate matter; the most widely used of which is the electrostatic precipitator (Figure 16.1), which can remove over 99 per cent particulate matter present in the exhaust from a thermal power plant. It has electrode wires that are maintained at several thousand volts, which produce a corona that releases electrons. These electrons attach to dust particles giving them a net negative charge. The collecting plates are grounded and attract the charged dust particles. The velocity of air between the plates must be low enough to allow the dust to fall. A scrubber (Figure 16.1) can remove gases like sulphur dioxide. In a scrubber, the exhaust is passed through a spray of water or lime.”
