Final answer:
A green catalyst is one that contains earth-abundant elements, improves reaction efficiency, and reduces production costs, thereby supporting sustainable chemistry. Therefore, correct option is 4.
Step-by-step explanation:
A green catalyst is one that accomplishes all of the following: it contains earth-abundant elements, makes reagents react more efficiently, and decreases the cost of producing a chemical.
The concept emphasizes sustainable and environmentally friendly chemical processes, which include the use of catalysts for enhancing reaction rates while reducing waste.
Catalysts aid by providing alternative pathways for reactions with lower activation energy and increasing the likelihood of molecules colliding in proper orientation.
By maximizing atom economy, they help to minimize the waste from chemical processes. Also, they are crucial because they are not consumed in the reaction, making them reusable and more cost-effective.