If a chemical change has taken place, which of these is most likely true? (5 points) Original substance can be easily recovered. Composition of a substance is the same. A completely new substance is formed. An easily reversible process has taken place.

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

This classification of drug typically changes the brain's chemistry and reduces its ability to create its own endorphins.

Draw the skeletal structures of two different molecules that are each made of 5 carbon atoms and 12 hydrogen atoms.