After a physical change, the substance always has the same ___ A. chemical properties
B. volume
C. mass
D. state

The density of glycerin is 1.26grams/centimeter cubed . how many is this? use the conversion rates of and . express your answer to the correct number of significant figures.

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.

Which class of molecules functions as chemical signals? hormones water carbohydrates proteins