Students in a laboratory are asked whether a given sample of liquid matter is a pure substance or a mixture. They brainstorm the following suggestions for a test to answer the question.
Test Description
1.Add NaOH(aq) to see if a precipitate forms
2.Evaporate it to see if a residue will form
3.Examine it under a microscope to see if it is uniform throughout
4.Run the liquid through a filter paper

Which of the above tests could yield useful information to the answer? (4D)
a. 2 only
b. 2, 3, and 4
c. 1, 2, and 4
d. All the tests will be useful