Question

Which statements are true in case of catalysts?
(This question has multiple correct answers)
(A) The catalyst is unchanged chemically at the end of a reaction.
(B) The catalyst accelerated the reaction.
(C) In a reversible reaction, the catalyst alters the equilibrium position.
(D) A small amount of catalyst is often sufficient to bring a large change in a reaction.

Answer 1

A catalyst is a chemical species that is used in a reaction to bring about a change in the speed of the reaction. Catalysts are of two types – positive catalysts or promoters and negative catalysts or inhibitors. However, catalysts themselves do not take part in a reaction.

Complete step by step answer:
A catalyst is used only as a supporter in a reaction to make it either faster or slower. It plays no role in forming the products after a reaction. So, its chemical properties do not get affected during a reaction and it remains chemically inert. So, it remains chemically unchanged at the end of a reaction.
Positive catalysts or promoters, as the name suggests, are the catalysts that bring about a positive change in the reaction or promote the reaction. Positive catalysts speed up the reactions and help them proceed faster. Therefore, it is true that a catalyst accelerates a reaction.
When a catalyst is used in a reversible reaction, it does not alter the reaction equilibrium. The amount of reactants and products formed at the end of a reaction remains the same as would be formed without the use of a catalyst. So, a catalyst does not alter the equilibrium position, but simply helps in reaching the equilibrium faster.
Even a small amount of catalyst is enough to reduce the activation energy of a reaction, thereby, helping the reaction to take place faster.
Therefore, it can be concluded that all the given statements regarding catalysts are true.

So, the correct answer is Option A,B,C,D .

Note: Activation energy can be defined as the minimum amount of energy that is needed to be supplied for a reaction to occur. Negative catalysts or inhibitors decrease the speed of a reaction by increasing the activation energy of the reaction.