In this task, you are given a question and answer for that. The answer will fill in the blank or will complete the unfinished question. Your task is to provide an explanation based on the given question or fill-in-the-blank statement, and answer.

Question: If Mona is creating a reaction using solid reactants and she decreases the surface area of those reactants, what happens to the reaction rate? 
 Answer: decreases
Therefore, increasing the surface area of solid reactants increases the reaction rate.

Question: Gerald laid down many rock layers. The layers on the bottom level were likely laid 
 Answer: first
Lower rock layers were laid down earlier, so they are assumed to contain older fossils.

Question: When two pieces of metal are rubbing together and oil is added between them the friction 
 Answer: decreases

To reduce friction, oil is added to the engine.