Astudent set up an experiment to show that carbon dioxide is produced by elodea plants during photosynthesis. she filled two test tubes with distilled water and placed a piece of elodea in each of the tubes. she added a drop of phenol red, which turns red in a basic solution and yellow in an acidic solution. she blew in each tube to add carbon dioxide, which caused the distilled water to become more acidic so the phenol red turned yellow. she wrapped tube a in aluminum foil and left tube b exposed to the light. after 15 minutes, what should she expect to observe?

After 15minutes, the water in test tube with the exposed Elodea plant will become colourless. While the solution with the wrapped Elodea plant will remain slightly yellow as it is.

Explanation:

The carbon dioxide introduced into each tube will lead to development of yellow coloration in the solutions. The exposed plant will use up more carbondioxide from the ones introduced in it's solution during the process of photosynthesis. This will disapprove the hypothesis formulated by the student, thereby returning the pH if the solution to it's neutral state. This will reverse the color to colourless nature of the distilled water. While the wrapped Elodea plant will not be able to use the available carbondioxide, therefore the solution will remain slightly acidic and the yellow color will remain.

it is b that is the answer.

on passing the small ampere of electric current through the tube made of ar and hg of cfl generates uv rays which excites the fluorescent and thus emits the high radiation by consumption of just 5- 12 w in comparison to incandescent light which requires more power such as around 40 - 55 w to lighten.

moreover the life span of fluorescent or cfl is around 8000 h whereas the life span of incandescent is around 1200 h

hence, the building installed with incandescent lights bears more electricity bill.