The color change shows this is a chemical change, because every time there is a color change this indicates a chemical change. the color change shows this is a chemical change, because adding the gas caused the unexpected color change. the color change shows this is a physical change, because the indicator only changed colors slightly. the color change shows this is a physical change, because blue and green are similar colors and the gas did not cause the change. bromothymol blue is a liquid indicator that changes color from blue to green when carbon dioxide gas is mixed into the solution. when carbon dioxide leaves the solution, the color of the indicator changes from green to blue. based on the information above, which of the following describes the kind of change present?

Bromothymol blue is a pH indicator used to measure the concentration of carbon dioxide present in solution.  It changes its color to green in presence of carbon dioxide gas.

It is present in solid form and can be protonated or deprotonated which creates changes in color either yellow or green.

The change in color of indicator indicates the chemical change as all this happening in presence of carbon dioxide gas

Thus, option B is correct

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.