What information does this computer model provide?

Question

Open this simulation and click the Macro tab. The simulation allows you to check the pH scale of various liquid solutions. To get started, go to the drop-down menu at the top of the page and select a liquid from the list. Use the dropper below the drop-down menu to add the liquid to the container. You can change the concentration of the solution by adding water using the tap on the right. You can also drain the solution using the tap near the left of the container. At any point, check the pH scale of the solution by dragging the green scope to the container. Try checking the pH level of different solutions, and then answer the following questions.

Answer 1

The simulation calculates "the pH scale of various liquid solutions."

 

It allows the user to "select a liquid," to "add the liquid to the container," then to "change the concentration of the solution by adding water" to the solution.  A convenient drain allows remove some of the current concentration.  

 

The simulation allow the user to "check the pH level of different solutions."  At any point, the user should know the amount of the liquid and the amount of water currently in the solution.