Question

two two example of negative and positive catlyast

Answer 1

Positive catalyst
     It is a catalyst which speeds up the rate of the reaction. 
 Examples: MnO2, V2O5, Pt 
 ii.  Negative catalyst
      It is a catalyst which reduces the rate of reaction. 
 Example: Alcohol 
 iii. Promoter 
      It is added to a catalyst to increase its efficiency. 
      Example: Molybdenum