1. which of these is an indication that a chemical reaction has occurred? a. formation of a precipitate b. melting of a substance c. boiling of a substance d. freezing of a substance 2. if decreases in temperature accompanies a reaction, what occurred? a. energy was destroyed b. energy was created c. energy was absorbed d. energy was released 3. which of these accurately describes the products of a reaction? a. new substances that are present at the end of a reaction b. substances that were not used up in a reaction c. substances that are used in a reaction d. substances that do not participate in a reaction 4. which of these describes an exothermic reaction? a. energy is released by the reaction b. energy is created in the reaction c. energy is absorbed by the reaction d. no energy is transferred by the reaction 5. what occurs in a chemical reaction a. reactants are formed without chemical bonds being broken b. reactants are formed from products by the breaking and forming of bonds c. products are formed without chemical bonds being broken d. products are formed reactants by the breaking and forming of new bonds.

1. an experiment in your science class lists the materials needed for the lab. it is your job, as a lab partner, to measure out 25 ml of distilled water and 2.5 grams of magnesium. what lab measuring tools would you choose to measure each substance and how would you use each tool to get the correct amounts? be sure to describe the process you would follow step-by-step. (5 points) 2.which of the following is an si base unit for measuring mass? (2 points) ampere gram meter pound 3.which of the following is an si base unit for time? (2 points) decades hours minutes seconds 4.which of the following tools should a scientist use to measure an object in milligrams? (2 points) graduated cylinder pan balance tape measure thermometer 4.which of the following tools should a scientist use to measure an object in milligrams? (2 points) graduated cylinder pan balance tape measure thermometer. 5.a pencil beside a metric ruler. the ruler is scaled from 1 centimeter to 10 centimeters, with markings for millimeters between each number. one end of the pencil is beside the 0 on the ruler, and the pencil point is beside the 5. which of the following measurements is accurate but not precise? (2 points) 5 mm 5 cm 50 mm 50 cm 6. which of the following prefixes represents the largest value? (2 points) giga hector kilo milli 7. which of the following types of graphs is best for plotting the percentages of a whole value in a data set? (2 points) bar graph circle graph histogram line graph