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.

[EX Q]: Question: If you were to launch a cannon which ball would fly faster if everything else were the same? 
 Answer: Lighter
[EX A]: The mass of the particles: lighter particles will diffuse faster, because on average they move faster.

[EX Q]: Question: If Mona shines a light through both wool and cotton and determines that cotton is more dense then wool, which material will the light move faster through? 
 Answer: wool
[EX A]: The more dense the medium, the slower the light moves.

[EX Q]: Question: If Mona fills up a cup with water and places that water into the freezer, what happens to the density of the water as it cools down? 
 Answer: increases
[EX A]:
When a volume of water is cooled, the molecules move less vigorously, so same number of molecules takes up less space and the water is denser.