Answer:
CLEANER
Explanation:
Independent variable is the variable in an experiment that is changed or manipulated by the experimenter in order to bring about a measurable response.
In this question, Marie notices that the current cleaner she is using on her shower is not cutting through the hard water build-up that has accumulated. She decides to purchase 3 other cleaners to see if one of them will do a better job of cutting through the stains. The CLEANERS being changed in this experiment is the INDEPENDENT VARIABLE.
Much of biological studies are actually chemistry because of chemical changes that occur within organisms. Similarly, large parts of chemistry are governed by physics.
Answer: Limitation: They may be more expensive and time consuming than lab experiments. Limitation: There is no control over extraneous variables that might bias the results. This makes it difficult for another researcher to replicate the study in exactly the same way.
Explanation:
Hope this helps!
In 1st orbit 2
2nd 8
3rd 10
f orbital has 16
