Encircle the letter of the correct answer. 16. ____________ property of matter can be readily observed without changing its composition. a. chemical b. physical c. electrical d. mechanical 17. ____________ property of matter needs to change first before a certain property can be observed. a. chemical b. physical c. electrical d. mechanical 18. What are the two effects on matter when there is a presence or absence of oxygen? a. sublimation and deposition b. evaporation and condensation c. combustion and rusting d. combustion and oxygenation 19. What are the three elements needed for fire to occur? a. water,gasoline, oil b. wood, leaves, wax c. oxygen, heat, fuel d. kerosene,wood,water 20. ____________ is a form of energy. It is described as how high the temperature is. a. Heat b. Water c. Wind d. Light 21. Whenever a material undergoes a chemical change, all of these are observed EXCEPT: a. Release of pressure b. Release of heat c. Formation of new product d. Formation of gas 22. What happens to water when heat is applied? a. evaporates b. freeze c. sublimate d. condensate 23. What happens to the fleshy part of the apple when you cut it for some time? a. The apple becomes dry and flaky. b. The apple changes its color. c. The apple changes its taste. d. The apple stays the same.