Answer:
Correct order for the four strokes in a four stroke engine is as follow:
1.(D) Piston moves down, allowing fuel-air mixture to enter intake valve
2.(A) Piston moves up, compressing gas and causing gas to increase its temperature
3.(C) Spark plug fires,causing combustion as gas is still compressed; increase in energy from combustion pushes piston down
4.(B) Piston moves up, pushing burned gases through exhaust valve
Explanation:
In a four stroke engine, four strokes takes place one after other to produce energy or power.
Correct order for these four strokes is given above that is
1. Piston moves down allowing fuel-air mixture to enter from intake valve. Actually moving down of piston creates a vacuum,that infact pulls fuel-air mixture from intake valve
2. Piston moves up causing compression, and due to compression temperature of mixture(fuel+air) increases
3. At the end of 2nd Stroke Spark Plug fires , and the mixture of compressed gases is combusted releasing energy, due to enegy release piston moves downward
4. Piston again moves upward causing burnt gases to move out from exhaust valve.