Which statement describes a change that occurs during a chemical reaction? a. atoms in the original substances are changed into different atoms to make new substances. b. atoms in the original substances are arranged in a different way to make new substances. c. the atoms in a substance change their properties so they can become a new substance. d. the atoms in a substance start to move faster until they are no longer touching each other.

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

Which statement best describes the flow of energy in this scenario

Avariable that is not being directly tested during an experiment should be changed varied experimented controlled