Which of the following is correct about enzymes?

The answer is (1) it reduces the activation energy.

Enzymes are biological catalysts that speed up chemical reactions. They do this by binding to the reactant molecules and providing a low-energy pathway for the reaction to take place. This lowers the activation energy of the reaction, which makes it more likely to occur.

Enzymes do not change the equilibrium constant of a reaction. The equilibrium constant is a measure of how much product is formed when a reaction reaches equilibrium. The enzyme does not change the number of reactant molecules or the number of product molecules, so it does not change the equilibrium constant.

Therefore, the only option that is correct about enzymes is that they reduce the activation energy.

The other options are incorrect. Option (2) it increases the activation energy, is incorrect because enzymes actually lower the activation energy. Option (3) it changes the equilibrium constant, is incorrect because enzymes do not change the equilibrium constant. Option (4) none of these, is incorrect because enzymes do reduce the activation energy.