Answer:
Hence the concentration of a MnO41- solution that has absorbance of 0.490 in the same cell at that wavelength is 0.3266.
Explanation:
Now A = el, el=const
Then,

They should identify the confounding variable.
Some condition that is not examined by the scientist might alter the experiment result. That condition is called confounding variable. If the method of the experiment same but result is very different, there should be unidentified confounding variable. It could be air humidity, temperature, ventilation, light, time of the year or anything that might not be seen by naked eye.
Try to redo the experiment with controlling variable as much as possible.
<h2>Answer : Option B) Ozone</h2><h3>Explanation :</h3>
The layer of atmosphere which contains a substance(Ozone) that was created from a product of living thins (oxygen) and protects living things (from harmful UV rays).
Oxygen in the atmosphere reacts in presence of UV rays and forms Ozone.
This ozone forms a protective layer around the earth and protects it from harmful UV rays.