15- Which of the following is not an internal combustion engine a) 2-stroke petrol engine b) 4-stroke petrol engine c) diesel engine d) gas turbine e) steam turbine 16- Which of the following medium is compressed in a Diesel engine cylinder? a) air alone b) c) d) e) air and fuel air and lub oil fuel alone air, fuel and lub oil. 17- Stirling engine can be called as: a) internal combustion engine b) external combustion engine c) combination of, internal and external combustion engine d) none. 18-In a four-stroke cycle engine, the four operations namely suction, compression, expansion and exhaust are completed in the number of revolutions of crankshaft equal to: a) four b) three c) two d) one. 19- In a two-stroke cycle engine, the operations namely suction, compression, expansion and exhaust are completed in the number of revolutions of crankshaft equal to a) four b) three c) two d) one. 20-The following is an S.I. engine a) diesel engine b) petrol engine. c) gas engine d) none of the above