24. most cleaning solutions like soap, with a ph of 8-9 are examples of a(n) a. acid b. base c. neutral substance 25. in a sample of 100 g of nitrogen, how much would be left after 20 minutes if the half life is 9.9 minutes? a. 75 g b. 50 g c. 25 g d. 12.5 g 26. what are the signs you can see that would show you a chemical reaction has occurred? a. color change, changing shape, and temperature change b. bubble formation, temperature change, and color change c. bubble formation, change in size, and color change d. change in state, color change, and bubble formation 27. which of the following is not a homogeneous mixture? a. italian salad dressing b. salt water c. chocolate pudding d. steel 28. if 6.25 grams of a sample of carbon is left after decaying over 22,920 years, how much of the sample did you start with? the half-life of carbon is 5,730 years. a. 100 grams b. 25 grams c. 50 grams d.75 grams 29. which of the following is not a property of an acid? a. tastes sour b. usually reacts with a metal c. changes the color of an indicator d. feels slippery 30. what atom would most likely form a covalent bond with carbon? a. sodium b. potassium c. chlorine d. gold