Q.Ethane burns completely in air to give CO₂, while in a limited supply of air gives CO. The same gases are found in automobile exhaust. Both CO and CO₂ are atmospheric pollutants.

Step 1. Danger of CO. Carbon monoxide is a poisonous gas produced by incomplete combustion (here, ethane burning with a limited air supply), released mainly by automobile exhaust. Its danger is chemical: it binds strongly with haemoglobin to form carboxyhaemoglobin.

Step 2. Danger of CO₂. Carbon dioxide, from complete combustion of ethane (and respiration, fossil-fuel burning, cement manufacture more generally), is not directly poisonous at the concentrations typically inhaled, but its rising atmospheric level is responsible for global warming, and it also causes headache and nausea.

Step 3. Effect of CO on the body. Carboxyhaemoglobin formation impairs the normal oxygen transport function of blood, reducing its oxygen-carrying capacity. This oxygen deficiency results in headache, dizziness, tension, loss of consciousness, blurring of eyesight and cardiac arrest. …

Treat CO and CO₂ separately since the question explicitly frames them as 'both' atmospheric pollutants -- CO's harm is acute/chemical (haemoglobin binding); CO₂'s harm is b …

• Treating CO and CO₂ as equally acutely toxic -- CO's mechanism (haemoglobin binding, oxygen starvation) is far more immediately dangerous than CO₂, whose main harm at typical concentra …