What evidence did you see or read about in the article that makes you think this?

Agroup of students is studying convection current. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other is in an area with warm air. after 10 minutes, the balloon are released from a height of 1 meter. which of the following to the students most likely observe? a) the warm balloon expands and rises. the cold balloon shrinks and sinks b) the balloon both rise. the cold balloon is larger than the warm balloon c) the cold balloon expands and rises. the warm balloon shrinks and sinks d) the balloon rise at the same rate. both balloons are the same size

How do you know when a chemical reaction has occurred

How can liquids be seperated by density a the liquids are absorbed onto a paper b the liquids are turned into seperate vapors c the liquids are collected as they evaporate d the liquids are allowed to seperate into layers