Which of the following is a physical change? a) sawing a piece of wood in half. b) burning a piece of wood. c) rust forming on an iron fence. d) a copper roof changing color from red to green.

How do you lengthen a pattern piece? (family and consumer science, sewing)

Which of the following statements is true about energy quantization at the atomic level? electrons in the outermost orbits are the most stable. electrons in all the orbits around the nucleus have the same amount of energy. electrons in the orbit closest to the nucleus have the least amount of energy. electrons absorb or release the same amount of energy independent of the energy levels.

Which statement is actually true about the relationship between activation energy and reaction rates? low activation energy barriers result in low rates. high activation energy barriers result in low rates. low activation energy barriers result in no reaction. high activation energy barriers result in no reaction.