Ozone formed during photochemical smog protects us from UV radiations.
Increase in tropospheric ozone can reduce food production.
Photochemical smog formation is maximum in morning and evening due to heavy traffic hours.
Vehicular exhaust does not contain any precursors of ozone formation in the troposphere.
Show Solution
The Correct Option isB
Solution and Explanation
Step 1: Think about where ozone sits:
Ozone high up in the stratosphere blocks UV. Ozone low in the troposphere is a toxic gas.
Step 2: Test (1):
It claims smog ozone gives UV cover. That mixes up the two layers, so it is wrong.
Step 3: Test (2):
Ozone enters leaf pores and damages plant cells. Damaged plants give less grain, so food output can drop. This agrees with the passage on crop damage.
Step 4: Test (3):
Smog needs sunlight to run its reactions. Dawn and dusk have little light, so the peak is at noon despite traffic. Statement is wrong.
Step 5: Test (4):
Exhaust gases carry nitrogen oxides and unburnt hydrocarbons, which are the ozone precursors. Statement is wrong.
Step 6: Conclude:
Only the crop-damage statement survives.
Final Answer:
The correct statement is (2).
\[ \boxed{2} \]
