21. If air fuel ratio of the mixture in petrol engine is more than 15:1

1. 1. NO_x is reduced

   
   
   

   2. CO₂ is reduced

   
   
   

   3. HC is reduced

   
   
   

   4. CO reduced

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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22. In order to burn 1 kilogram of CH₄ completely, the minimum number of kilograms of oxygen needed is (take atomic weights of H, C and O as 1, 12 and 16 respectively)

1. 1. 3

   
   
   

   2. 4

   
   
   

   3. 5

   
   
   

   4. 6

   
   
   

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1. View Hint View Answer Discuss in Forum

   

   Correct Option: B

   

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23. The silencer of an internal combustion engine

1. 1. reduces noise

   
   
   

   2. decrease break specific fuel consumption (BSFC)

   
   
   

   3. increase BSFC

   
   
   

   4. has no effect on its efficiency

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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