At the end of the chemical reaction the catalyst remains

The correct answer is option 2. Key Points

• A catalyst is a substance that can be added to a reaction to enhance the reaction rate without getting consumed in the process.
• Catalysts typically speed up a reaction by lowering the activation energy or changing the reaction mechanism.
• These catalysts can be recovered at the end of the reaction and reused as they do not get altered in any way during the reaction.
• Enzymes are proteins that act as catalysts in biochemical reactions.
• A Catalyst remains unchanged in mass and chemical compositions at the end of reactions. However, its physical state can be changed. 

• So, At the end of the chemical reaction, the catalyst such as granular MnO2 may be left as a finely divided powder, but not changed in composition chemically or it's mass.

Important Points

• A stoichiometric amount of one reactant can mean the amount that will react completely with a given amount of another reactant, leaving no excess of either one.
• Catalyst does not take part in balancing the chemical reaction hence catalysts are not required in Stoichiometric amounts.
• The most common catalysts are - Aluminosilicates, Iron, Vanadium, Nickel, Platinum + Alumina.

Additional Information

• A positive catalyst is a substance that increases the rate of reaction or the speed of the reaction without getting consumed in the process.
• Catalysts can be of 2 types:

1. Homogenous catalysts- those catalysts which are in the same phase or state (mostly liquid or gas) as the reactants.
2. Heterogeneous catalysts- those catalysts which are in a different phase than the reactants.

• Catalysts that are involved in biochemical reactions are called enzymes.