12. 12

13. 13.

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17. Joshua placed 4 grams of baking soda in a balloon and 200mL of vinegar in an Erlenmeyer flask. After stretching the opening of the balloon across the neck of the flask, the student raised it to dump the baking soda into the flask. He immediately observed foaming bubbles in the flask and the balloon began to expand, Joshua concluded that a.the bubbles indicated a chemical change was occurring b.the gas was hydrogen c.the baking soda and vinegar were products of a chemical reaction d.a physical change only was occurring 17

18. Which of the following is an example of a physical change? a.Mixing baking soda and vinegar together, and this causes bubbles and foam. b.A glass cup falls from the counter and shatters on the ground. c.Lighting a piece of paper on fire and the paper burns up and leaves ashes. d.Baking a birthday cake for your mother. 18

19. Which of the following is an example of chemical change? a.Filling up a balloon with hot air. b.Taking a glass of water and freezing it by placing it in the freezer. c.A plant collecting sunlight and turning it into food. d.d.Your dog ripping up your homework 19

20. The diagram below shows a geometric model of A water molecule What do the symbols and Represent in the model a.Genetic material b.Chemical bonds c.Cells d.atoms 20

21. In the reaction below which pair of compounds represents the products of the reaction? a. CaSO 4 + 2NaCl b.CaCl 2 + Na 2 SO 4 c.CaCl 2 and 2NaCl d.CaSO 4 and Na 2 SO 4 21

22. Coal contains carbon and other elements. Carbon dioxide forms when coal burns in the presence of oxygen. Which of these is the best evidence that a chemical reaction occurs when coal burns? a.The shape of the coal changes b.Oxygen is present c.A new substance is produced d.Coal is made up of more than one element. 22

23. Some students in a chemistry lab conducted an investigation in which they added four different solid substances to separate beakers of water. They stirred the mixtures for one minute and then recorded their observations in the table below. What substance most likely caused a new substance to be formed when mixed with water? a.substance 1 b.substance 2 c.substance 3 d.substance 4 23

24. When the fuse ignites the contents of a firework, oxygen is consumed as a result of what type of reaction? a.Mass c.Chemical b.Phase d.Nuclear 24

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