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.

Example Input: Question: Mike is watching how particles of reactants function, and sees that they are very far apart. Considering that the concentration of them is very low, the chance of them colliding together is 
 Answer: low
Example Output: At higher concentrations, particles of reactants are crowded closer together, so they are more likely to collide and react.

Example Input: Question: Air pressure is higher in the 
 Answer: valleys.
Example Output: Air pressure is less at higher elevations.

Example Input: Question: If Jim wants to raise the pH of his solution he should do what to the concentration of hydrogen ions inside of it? 
 Answer: decrease
Example Output:
With a higher the concentration of hydrogen ions, a solution is more acidic and has a lower pH.