16. The power output from a spark ignition engine is varied by

1. 1. Changing the ignition timing

   
   
   

   2. Regulating the amount of air-fuel inducted

   
   
   

   3. Regulating the amount of air fuel mixture

   
   
   

   4. Regulating the amount of fuel

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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17. For determining the ignition quality of compression ignition engine fuels, the reference fuels used are

1. 1. Isooctane and n-heptane

   
   
   

   2. Cetane and α -methylnapthalene

   
   
   

   3. Hexadecane and n-heptane

   
   
   

   4. Cetane and isooctane

   
   
   

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1. View Hint View Answer Discuss in Forum

   Cetane and α -methylnapthalene

   Correct Option: B

   Cetane and α -methylnapthalene

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18. Alcohols are unsuitable at diesel engine fuels because

1. 1. The cetane number of alcohol fuels is very low which prevents their ignition by compression

   
   
   

   2. The cetane number of alcohol fuels is very high which prevents their ignition by compression

   
   
   

   3. The cetane number of alcohol fuels is very low which prevents good combustion

   
   
   

   4. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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