Answer:
This is an controlled experiment because he is only changing the amount of carbon dioxide in the air. Since he is only changing one variable at a time and comparing it to a natural, unaltered tomatoe area, his experiment is controlled.
Explanation:
The definition of a controlled experiment is a test where the person conducting the test only changes one variable at a time in order to isolate the results. An experiment where all subjects involved in the experiment are treated exactly the same except for one deviation is an example of a control experiment.
The thing that would mostly make the results of the experiment invalid would be the students themselves. No one is built the same, and the exact same food can have very different effects on different people.
Answer:
Answer is D, Heart rate monitor.
Explanation:
It is known to be true that during exercise, the rate of the heart beat increases, and this is good for our heart to keep on functioning properly.
A heart rate monitor is usually a chest strap device to measure and sometimes record the rate of the heart's activities such as rate and rhythm. This device is with electrode sensors for transmitting heart rate to an app. Example of a heart rate monitor is Holter monitor.
They form an ionic bond by exchanging one electron