Answer: 5
Explanation: you divide the distance by the time and get the speed.
Answer: Carbon dioxide is a pure substance.
Explanation: A pure substance is defined when a substance has a single type of molecule. If more than 1 type of molecule is present in a substance, then it is considered as a mixture.
- Soda is basically a mixture of water and carbon dioxide. More than 1 type of molecule is present.
- Gasoline is a mixture of may gases. More than 1 type of molecule is present.
- Salt water contains salt and water molecules, hence it is considered as a mixture.
- Carbon dioxide has only 1 type of molecule which is
molecules. Hence, it is a pure substance.
The fact that the student used different amount of water (another independent variable) is wrong with the experimental design
WHAT ARE THE COMPONENTS OF AN EXPERIMENT?
- An experiment aims at solving a scientific problem or answering a scientific question. An experiment should contain a variable being changed called INDEPENDENT VARIABLE and a variable being measured called DEPENDENT VARIABLE.
- In an ideal experiment, only one independent variable should be used while every other variable should be kept constant. This is done so as not to affect the result of the experiment.
In the experiment conducted by the student in this question, two independent variables were used i.e. the different amount of water and the different temperatures. This is what is wrong about the experimental design.
- In a nutshell, the fact that two independent variables were used by the student is what is wrong about the experimental design.
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