Air Quality Indices Visibility

To determine atmospheric stability, compare the environmental lapse rate with the adiabatic lapse rate (temperature decrease with height). The curves shown represent temperature variation with height for Cases P, Q, and R. Step 1: Analyze Case P.
Case P shows temperature decreasing significantly with height. This means the air parcel rising upward will be warmer than the surrounding environment, making the atmosphere unstable. Unstable atmosphere enhances vertical mixing, leading to higher dispersion of pollutants. Thus, option (A) is correct.
Step 2: Analyze Case Q.
Case Q shows a sharply increasing temperature with height → strong inversion. This is an elevated inversion, which suppresses vertical mixing. This results in lower dispersion, not higher. Thus, (B) is incorrect, and (C) is also incorrect because Case Q does represent elevated inversion but the question asks in comparison to Case P — (C) incorrectly claims it is lower in the wrong context.
Step 3: Analyze Case R.
Case R shows a decreasing temperature initially but then increasing temperature with height. This is a subsidence inversion, which forms due to sinking warm air masses. It also suppresses vertical dispersion. Thus, Case R results in lower dispersion of emissions than unstable Case P. Therefore, (D) is correct.
Final Answer: (A), (D)

Step 1: Recall the NAQI calculation rule.
The National Air Quality Index (2015) uses sub-indices for each pollutant (NO , SO , PM , PM , O , CO, NH , Pb, etc.). The overall NAQI is defined as the maximum of these sub-indices, not the average or sum. This is because the pollutant with the worst effect on health should decide the overall quality.
Step 2: Apply the given values.
- Sub-index for NO - Sub-index for SO - Sub-index for PM
Step 3: Choose the maximum.
The overall NAQI = .
Step 4: Eliminate wrong options.
- Option (A) 80 → wrong, because not the maximum. - Option (B) 260 → wrong, because NAQI is not calculated by adding values. - Option (D) 151 → wrong, because NAQI is not calculated by averaging values. Therefore, the correct answer is 100. Final Answer: