Question

A catalyst is a substance which increases the rate of the reaction without itself undergoing any change.
A) True
B) False

Answer 1

Hint: Before saying a comment on the statement, we should have a minimum idea of the catalyst. Enzymes in our body which have a very important role in many life processes are a catalyst.

Complete step by step answer:
So in the question we are given a statement and we have to comment whether the statement is true or not.
The statement given is about the catalyst, that whether the catalyst is a substance that increases the rate of reaction without undergoing any change by itself.
For commenting the statement we should know what is a catalyst and why is it used and how it works.
Catalyst is generally defined as that substance which on adding with the reaction mixture, alters the rate of the reaction without being consumed by the reactant to form the product i.e. the catalyst does not undergo any change in the chemical reaction.
Then comes the question: why is it used? A catalyst is always used to increase or more correctly may be said as to alter the rate of the chemical reaction. As the catalyst only provides a favorable condition or surface on which the reactants could react easily and effectively to give the favored products.
And the next question is the principle behind the catalyst. As we said earlier catalyst is not involved directly in the chemical reactions it is only providing a favorable condition for the reaction to proceed. The catalyst reduces the activation energy of the chemical reaction, so that the chemical reaction could proceed easily.
The activation energy is that extra minimum energy that is required for the reactant molecules or the atoms to undergo a chemical transformation and to yield a product. As the catalyst reduces the activation energy more reactant can be converted into product which increases the rate of reaction.
So we can conclude that catalyst is a substance which increases the rate of reaction without itself undergoing any change in the chemical reaction.

So the statement given in the question is true and the correct option is option (A).

Note: There are two types of catalysts i.e. positive catalysts which increases the rate of reaction and negative catalysts which decreases the rate of the chemical reaction.
The example for positive catalyst is manganese dioxide and for negative catalyst is phosphoric acid.