What is the percent by mass of oxygen fe2o3 (formula mass= 160)?

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.

Ahypothesis must be testable and falsifiable to be considered scientific a. trueb. false

Which molecules are more strongly attracted to one another -c3h8o molecules that make up liquid rubbing alcohol or ch4 molecules that make up methane gas