Oxides of nitrogen in the engines exhaust can be reduced by the following methods:
1. Decrease in compression ratio
2. Exhaust gas recirculation
3. Use of 5% lean mixture
4. Use of oxidation catalysts in exhaust manifold.
The correct methods are

A. To prevent pressure build up B. To prevent temperature build up C. To increase the blow by gas D. To reduce the combustion leak

A. Exhaust system and intake system B. Crank case and intake system C. Crank case and exhaust system D. Exhaust system and catalytic converter

A. 20% B. 30% C. 35% D. 40%

A. Throttle body B. Intake manifold chamber C. Intake ports D. Combustion chambers