Question

in an experiment, students compared antibacterial hand - sanitizer to regular hand soap. they washed their hands with either sanitizer or soap and warm water for two minutes, then dried them with a paper towel. the control group used only warm water (no soap or sanitizer), while the experimental group used soap and hand sanitizer. after washing their hands, the students swabbed their hands and applied the swabbed samples to culture plates and incubated them. they later counted and recorded the bacterial growth as shown in the data table.

1. based on the data, the students concluded that the hand sanitizer was the most effective at killing bacteria. how would you respond to the students conclusion?

steve uses balloons to investigate the expansion and contraction of gases at different temperatures. he knows that particles move faster at higher temperatures. he develops the hypothesis that faster particle motion makes gases expand. he fills three balloons with the same amount of gas, places them at different temperatures and measures the circumference of each balloon.

1. which type of scientific investigation did steve choose for his experiment?
2. what tool will be useful to collect the information that he needs?
3. what is the independent variable from this experiment?
4. what is the dependent variable from this experiment?
5. what are at least 2 controlled variables from this experiment?

jenny bravo loves orville redenbacher popcorn, but she wants to know which brand of popcorn pops the most popcorn. she conducted an experiment by popping orville redenbacher popcorn, jiffy pop popcorn, and movietime popcorn for the same amount of time in the same microwave. she then counted all the un - popped kernels and determined which brand pops the most popcorn by the fewest number of un - popped kernels. identify the variables of this experiment.

1. what is the independent variable?
2. what is the dependent variable?

Explanation:

1. The students' conclusion may be inaccurate as the data shows hand - sanitizer has 28 bacterial colonies while Soap A has only 12. More analysis and replicates might be needed.
2. Steve's investigation is a laboratory experiment as he controls variables in a controlled environment.
3. A tape measure would be useful to measure the circumference of the balloons to collect the necessary information.
4. The independent variable is the temperature as it is the variable that Steve changes.
5. The dependent variable is the circumference of the balloon as it is affected by the temperature.
6. Controlled variables include the amount of gas in the balloons and the type of balloon.
7. The independent variable is the brand of popcorn as it is what Jenny changes.
8. The dependent variable is the number of un - popped kernels as it depends on the brand of popcorn.

Answer:

1. The conclusion may be wrong; more analysis needed.
2. Laboratory experiment
3. Tape measure
4. Temperature
5. Circumference of the balloon
6. Amount of gas, type of balloon
7. Brand of popcorn
8. Number of un - popped kernels