Question

A catalyst either___________ or ____________ the rate of chemical change but itself remains_____________at the end of the reaction.

• A. increases,decreases
• B. unaffected

Answer 1

Catalyst:

• A catalyst can increase or decrease the rate of reaction, without itself undergoing any change.
• A catalyst is a substance that increases or decreases the rate of reaction but remains unchanged at the end of the reaction.
• For example Potassium chlorate decomposes at $230°\mathrm{C}$ instead of $400°\mathrm{C}$ if heated in the presence of manganese dioxide$\left({\mathrm{MnO}}_2\right)$ (Catalyst).
• A substance that increases the efficiency of a catalyst is known as the promoter.

Therefore, A catalyst either increases or decreases the rate of chemical change but itself remains unaffected at the end of the reaction.