In a reaction of the type A+B -> C+D one could ensure it to be a first order reaction by : A. Increasing the temperature B. Increasing the concentration of a product C. Increasing the concentration of a reactant D. Adding a catalyst

The correct answer is: C. Increasing the concentration

A first-order reaction is a chemical reaction whose rate is proportional to the concentration of only one reactant. This means that if we double the concentration of the reactant, the rate of the reaction will also double.

Increasing the concentration of a reactant will increase the number of collisions between reactant molecules, which will increase the rate of the reaction.

The other options are incorrect because:

• Increasing the temperature will increase the rate of any reaction, but it will not necessarily make it a first-order reaction.
• Increasing the concentration of a product will not affect the rate of the reaction, because the product is not involved in the rate-determining step.
• Adding a catalyst will increase the rate of any reaction, but it will not necessarily make it a first-order reaction.