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Questions (72 - 82)
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In this lesson, questions (72 - 82) 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

Unacademy user
I think mcq should b taken from previous years prelim questions
how supercharging helps scavenging?
plz speak in English ur explanation are in Hindi we unable to understand Hindi
  1. COURSE: Question on I C Engine Lesson: Question (72-82)


  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 72 Consider the following statements regarding knock rating of SI engine fuels: 1. Iso-octane is assigned a rating of zero octane number. 2. Normal heptane is assigned a rating of hundred octane number 3. Iso-octane is assigned a rating of hundred octane number 4. Normal heptane is assigned a rating of zero octane number Which of the above statements are correct? (a) 1 and 2 (b) 2 and 3 (c) 3 and 4 (d) 4 and 1 Ans C


  4. Question 73 Assertion (A): Octane number is used for rating of fuels in spark ignition engine. Reason (R): Octane number of a fuel is defined as percentage by volume, of iso-octane in a mixture of iso-octane and ex-methylnaphthalene. (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 Ans: C


  5. Question 74 The two reference fuels used for cetane rating are (a) cetane and iso-octane (c) cetane and n-heptane (b) cetane and tetraethyl lead (d) cetane and -methyl naphthalene Ans d


  6. Question 75 The Cetane number of automotive diesel fuel used in India is in which one of the following ranges? (a) 30 40 (b) 41- 50 (c) 51-60 (d) 61-70 Ans b


  7. Question 76 Consider the following statements regarding n-Cetane: 1. It is a standard fuel used for knock rating of diesel engines. 2. Its chemical name is n-hexadecane 3. It is a saturated hydrocarbon of paraffin series. 4. It has long carbon chain structure Of the above correct statements are (a) 1, 3 and 4 (b) 1, 2 and 3 (c) 1, 2 and 4 (d) 2, 3 and 4 Ans : a


  8. Question 77 What is the main objective of supercharging of the engine? (a) To reduce the mass of the engine per brake power (b) To reduce space occupied by engine (c) To increase the power output of engine (d) All of the above Ans d


  9. Question 78 Consider the following statements: 1. Supercharging increases the power output of an engine 2. Supercharging increases the brake thermal efficiency considerably. 3. Supercharging helps scavenging of cylinders. Which of the statements given above are correct? (a) Only 1 and 2 (c) Only 1 and 3 (b) Only 2 and 3 (d) 1,2 and 3 Ans d


  10. Question 79 Surging basically implies (a) Unsteady, periodic and reversed flow. (b) Forward motion of air at a speed above sonic velocity. (c) The surging action due to the blast of air produced in a compressor (d) Forward movement of aircraft. Ans a


  11. Question 81 Assertion (A): The CI engine is basically more suitable for supercharging than the SI engine Reason (R): In the CI engine supercharging tends to prevent diesel 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 Ans a


  12. THANK YOU