Jessica took a mylar balloon outside on a very cold day. as she waited for the bus the balloon began to shrink. what is the best explanation of this?

Because the balloon is closed, the number of helium atoms inside doesn’t change as you cool it or warm it. But that doesn’t indicate that the balloon’s size is fixed. What is happening here is related to the relationship between three important properties of a gas: its temperature, its pressure, and its volume. As the balloon is cooled down, its volume decreases so as to keep the internal pressure in balance with the ambient air pressure. When the balloon is heated later on, the volume increases to maintain this same pressure balance.

good for her? ? where is the question?

"i have always loved contemporary art and made it a general goal to work within the field. after a few nonprofit internships at museums and galleries, i decided to try the for-profit art world and was offered a job as the ad assistant at the magazine. i much prefer the pace of the for-profit art community and have stayed with the company for three years, with a promotion to an account manager last spring."

i just did this and got a 100.