Question

Please read the question and answers closely before you say It's my fault.

The pH indicator bromothymol blue is blue in an alkaline solution and yellow in an acidic solution. A slight increase in acidity, such as when CO2 gas is added, causes a solution with the indicator to change from blue to yellow.
a solution with the indicator would turn from blue to yellow when which combination of factor exists? Select the two correct answers
A. Algae in the solution are placed under a bright light
B. Yeast cells and sugar are placed in the solution
C. A water plant in the solution is placed on a sunny windowsill
D. A person blows air into the solution through a straw
The correct options for me were B and C for ap*x

Answer 1

B

Step-by-step explanation:

The pH indicator bromothymol blue is blue in alkaline solution and yellow in an acidic solution. A solution in which the color of the indicator is yellow is already acidic, hence, to change the color to blue would require that the pH of the solution is increased from acidic to basic.

Yeast cell and sugar placed in the solution will result in the fermentation and further increase the acidity of the solution.

Water plants under bright light in the solution will consume CO2 and photosynthesize, thereby reducing the acidity of the solution.

Algae placed in the solution and left in the dark room will increase the acidity of the solution as a result of further addition of CO2 through the respiration of the algae.

A person blowing air into the solution through a straw will further increase the acidity of the solution due to the CO2 content of the air blown.

Therefore, the only action that will likely reduce the acidity of the solution by increasing the pH and thus turn the color of the indicator from yellow to blue is the presence of water plants in the solution placed under a bright lamp.