JAMB - Chemistry (2006 - No. 5)

Surface area refers to the total area of the exposed surface of a substance involved in a chemical reaction, essentially the amount of space where reactants can come into contact with each other, which significantly impacts the rate of a reaction; a larger surface area generally leads to a faster reaction rate because more reactant particles can collide and interact with each other. 

The efficiency of a solid catalyst to increase reaction rates depends on its surface area because a larger surface area provides more active sites for reactants to attach. This increases the rate of chemical reactions by facilitating more frequent collisions between reactant molecules and the catalyst.