Chris is about to do an experiment to measure the density of water at several temperatures. His teacher has him prepare and sign a safety contract before beginning the experiment. Which item is most likely part of the safety contract?
Researchers conducted an experiment to identify the effects of three different hand sanitizers on the growth of bacteria. The researchers grew one type of bacteria in twenty-four identical covered petri dishes. Then, they opened eighteen petri dishes and applied the three hand sanitizers to six petri dishes each. They left the remaining six petri dishes closed as a control group. When the researchers measured the growth of bacteria two days later, the six dishes that had no hand sanitizer showed the least amount of bacterial growth. The researchers concluded that not using any hand sanitizer would lead to the least bacterial growth. Which statement best explains why the researchers’ conclusion was not justified?
When analyzing the results of a scientific experiment, Kevin should base his conclusion on
A scientist wants to use a model to help present the results of his detailed scientific investigation. Why would a model be useful?
Which is always the first step in dealing with an accident in the lab?
Which of these steps would most likely be part of a lab procedure?
Which tool was most likely used in a procedure if the lab report shows that approximately 300 mL of water was used?
Which tool can be used to measure the volume of a liquid to one decimal place?
A scientist collected the following data, which show how the pressure of water vapor changes with temperature.Temperature (°C)Pressure (mm Hg)04.5109.62019.1 30 33.24058.75095.6What would a scientist do to best communicate these data to other scientists in a presentation?
The table shows five items that a person may consider including in a safety contract. Item numberItem1Label all containers.2Tie long hair back.3Bring a cell phone to the lab in case of emergency.4Bring a small laptop computer to the lab to use MSDS online.5Wear safety goggles at all times.Which three of the five items would be best to include in a safety contract?
Which best describes Internet wikis as a source of scientific information?
Miranda gets a small cut on her thumb after she breaks a beaker, and she begins to look around for the lab first aid kit. What important first step should she have taken?
The teacher prepares 2.50 liters (L) of a salt solution for a class experiment. How many quarts (qt) are in 2.50 L? (1 L =1.06 qt)
What is one advantage of using a computer over a graphing calculator?
A filmmaker wants to depict a realistic dramatization of a scientist making and communicating an important scientific discovery. Which plot description would best depict the methods of discovery and communication that a modern professional scientist uses?
Jerome and a classmate are conducting an experiment. Which piece of safety equipment is least likely to be at Jerome’s lab station?
Sian wants to measure the number of seconds that it takes for the contents of a beaker to change from clear to purple. Which of these tools should she use for this purpose?
Carlos is analyzing the results of a recent scientific study about gravity. Scientists recorded that the experimental value of gravity was 10.24 m/s² and the general accepted value of gravity is 9.81 m/s².
In the seventeenth century, Robert Hooke conducted many experiments with springs. In all the data he recorded, he found that the force needed to push down on a spring or stretch it out from its usual resting point was equal to the spring’s stiffness multiplied by the distance it is pushed or pulled from its resting point. He wrote the equation F = kX, in which F is the force, k is the spring’s stiffness, and X is the distance the end of the spring moves from its usual resting point when no push or pull is applied. The equation is still used today.
In the nineteenth century, Gregor Mendel first determined some basic rules of genetics that have been observed throughout all types of life. No observations have disproved these basic rules of genetics. Charles Darwin developed the idea of biological evolution around the same time, but he was unaware of Mendel’s discoveries in genetics. Over a century later, Darwin’s idea of evolution was modified in order to incorporate Mendel’s rules of genetics along with the other evidence that Darwin had used.
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