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Questions (52 - 60)
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In this lesson, questions (52 - 60) have been explained.

Harshit Aggarwal
Cleared UPSC ESE twice with Rank 63 and 90 in mechanical engg. Got 99 percentile in GATE. Cracked ONGC, BHEL,ISRO, SAIL, GAIL successfully

U
Unacademy user
sir please make a video Ray optic class12.
Uttam Singh
9 months ago
ok sure.
  1. COURSE: Question on I C Engine Lesson: Question (52-60)


  2. About me Graduated from NIT Nagpur in 2008 Cleared Engineering Services Examination (ESE-UPSC) Exam Got the offer letter from most of the Maharatna and Navratna Companies Cleared GATE Exam Rate, Review, Recommend, Share Follow me on Unacademy at: https://unacademy.in/user/harshit aggarwal


  3. Question 52 Consider the following statements Knock in the SI engine can be reduced by 1. Supercharging 2. Retarding the spark. 3. Using a fuel of long straight chain structure 4. Increasing the engine speed. Of these correct statements are (a) 1 and 2 (b) 2 and 3 (c) 1, 3 and 4 (d) 2 and 4 Ans d


  4. Question 53 Consider the following statements 1. Octane rating of gasoline is based on iso-octane and iso-heptane fuels which are paraffin 2. Tetraethyl lead is added to gasoline to increase octane number 3. Ethylene di-bromide is added as scavenging agent to remove lead deposits on spark plugs 4. Surface ignition need not necessarily cause knocking. Which of these statements are correct? (a) 1, 2, 3 and 4 (b) 2, 3 and 4 (c) 1 and4 (d) 1,2 and3 Ans : b


  5. Question 54 The volumetric efficiency of a well designed SI engine is in the range of (a) 40%-50% (c) 60%-70% (b) 50%-60% (d) 70%-90% Ans: d


  6. Question 55 A two-stroke engine has a speed of 750 rpm. A four-stroke engine having an identical cylinder size runs at 1500 rpm. The theoretical output of the two- stroke engine will (a) Be twice that of the four-stroke engine (b) Be half that of the four-stroke engine (c) Be the same as that of the four-stroke (d) Depend upon whether it is a C.I. or S.I. engine Ans : C


  7. Question 56 For same power output and same compression ratio, as compared to two stroke engines, four-stroke S.I. engines have: (a) Higher fuel consumption (c) Higher exhaust temperatures (b) lower thermal efficiency (d) higher thermal efficiency Ans: d


  8. Question 57 The knocking tendency in compression ignition engines increases with: (a) Increase of coolant water temperature (b) Increase of temperature of inlet air (c) Decrease of compression ratio (d) Increase of compression ratio Ans : c


  9. Question 58 Assertion (A): A very high compression ratio is favoured for a CI engine, in order to attain high mechanical efficiency without knocking. Reason (R): The delay period in CI combustion affects rate of pressure rise and hence knocking (a) Both A and R are individually true and R is the correct explanation of A (b) Both A and R are individually true but R is not the correct explanation of A (c) A is true but R is false (d) A is false but R is true


  10. Solution 58 A very high compression ratio is favoured for a CI engine, in order to attain high THERMAL efficiency without knocking Ans d


  11. Question 60 Consider the following measures: 1. Increasing the compression ratio 2. Increasing the intake air temperature. 3. Increasing the length to diameter ratio of the cylinder. 4. Increasing the engine speed. The measures necessary to reduce the tendency to knock in CI engines would include (a) 1, 2 and 3 (b) 1, 2 and 4 (c) 1, 3 and 4 (d) 2, 3 and 4 Ans a