Assertion (A) : Ground level concentration of pollutants decreases when taller stacks are used.
Reason (R) : The ground level concentration varies inversely proportional to the height of the stacks.
Codes :
UGC NET - 2014,
Answer: C
The assertion is true and the reason is false. Ground level concentration of pollutants falls when taller stacks are used, because the plume is released higher and mixes over a larger volume before reaching the ground.
The ground level concentration varies inversely as the square of the effective stack height, not inversely with the height itself, so the reason is wrong and the answer is option C.
Effective stack height is the physical height plus the plume rise, which is why tall stacks with hot plumes carry the pollutants to a greater height before they spread out.
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