(The tests in the following question were presented as a demonstration question on an hour examination.)
Four colorless liquids, I, II, III, and IV, could be water, a 1 M solution of an acid, a solution of a buffer, or a 1 M solution of a base. 25 mL of each unknown was added to a different test tube.
The unknowns are tested as follows. After testing is complete, identify each solution.
Test I: Addition of 4 drops of universal indicator to 25 mL samples of each liquid gives the colors shown.
Test II: Two drops of 4 M NaOH are added to each of the solutions from Test I.
Test III: Four drops of 4 M HCl are added to each of the solutions from Test II.
Solution I is _____________.
Solution II is _____________.
Solution III is _____________.
Solution IV is _____________.