Scientists conduct investigations to answer questions. before making a valid conclusion, scientists must * 1 point a collect relevant evidence b tell people about the data c publish results from the investigation d discuss the investigation with other scientists 3. ethan is observing chemical and physical properties of a substance. he heats a substance and observes that the substance turns from a brown solid to a black powder. he refers to several chemistry journals that claim this represents a chemical reaction. from his observation and research, he concludes that the substance goes through a chemical change when heated. how can ethan best defend his conclusion? * 1 point a by demonstrating that the substance will eventually melt if the temperature continues to increase b by verifying that the substance is now made up of different molecules than before it was heated c by verifying that the substance is made up of only one type of element d by demonstrating that the substance is less dense after it is heated 4.you are given a solution of sugar and sand in water. your task is to separate the sugar from the sand. which of the following experimental designs would you choose? * 1 point a filter out the sand and evaporate the water. b filter out the sugar. c let the solution stand for several minutes to let the sugar and sand settle out. d use a magnet to separate the sugar from the sand. 5.before 1896, many scientists concluded that light could not pass through black paper. in 1896, henri becquerel observed that uranium salts could cause a plate covered by black paper to react as if light had reached it. how did this observation affect conclusions about light passing through black paper? * 1 point a scientists ignored becquerel’s evidence because uranium is dangerous to use, so his study was not valid. b scientists repeated becquerel’s experiment until it no longer worked and reported that his conclusions were not valid. c scientists had to revise their earlier conclusion because evidence from becquerel did not support the original conclusion. d scientists stood behind the earlier conclusion that black paper blocks light because it was already an accepted conclusion. 6. a science teacher was curious to see whether offering money for good grades would increase student performance on a test. the teacher offered half of the students in the class $5.00 if they got an a on their next test. the other half of the class was not offered any money. what is the independent variable in this experiment? * 1 point a the number of questions on the test b the number of students in the class c the student’s grade on the test d the amount of money offered 7. jared investigated chemical reactions based on smell, color change, and release of bubbles. what type of evidence would support any conclusion jared makes? * 1 point a an observation b an estimation c a calculation d a measurement use the prompt and information below to answer question #8. 8. one of the scientists wants to run the experiment a second time but provide different amounts of oil for each colony of bacteria. how would this affect the validity of any conclusion for this experimental design? * 1 point a it would be valid because three different bacteria were tested. b. it would be valid because the experiment was conducted two times. c. it would not be valid because the amount of bacteria will still consume the oil. d. it would not be valid because the amount of oil provided is not being controlled. 9. which of the following is a qualitative observation? * 1 point a. the leaf is 9cm long. b. the mass of the computer is 1.5 kg c. the plant is tall. d. the temperature of the room increases by 8 degrees c. 10. which of the following is true of an independent variable? * 1 point a. independent variables are also called responding variables. b. independent variables depend on the depending variable. c. there can be more than 1 independent variable in an experiment. d. independent variable is the part of the experiment that is manipulated or tested by the experimenter.