4 Holly has an unknown substance in a beaker. She wants to determine the relative pH of the unknown substance. She places a piece of blue litmus paper into the substance, and the litmus paper stays blue. The substance in the beaker A. is a base. B. has a neutral pH. C. is an acid. D. does not have a pH.

Litmus paper can come in both red and blue. If Litmus paper turns blue, then it indicates that the solution is a base, whereas red indicates that the solution is an acid. If you dip a blue piece of litmus paper into a basic solution, it will remain blue. The same goes for placing a red piece of litmus paper in an acidic solution - it would stay red. So, your answer would be A.