Please I need help.

Suppose you performed a distillation of a solution containing butyl alcohol (C4H10O, also known as 1-butanol), sec-butyl alcohol (C4H10O, also known as 2-butanol), and ethyl alcohol (C2H6O). Butyl alcohol and sec-butyl alcohol have the same chemical formula, but they do have a different arrangement of their atoms (i.e. they are shaped differently), so this makes them have slightly different properties from one another. During the distillation, you collect the FIRST product that comes out, and set it aside. Then, you collect the SECOND product, analyze it, and determine that it has a formula mass of approximately 74 amu. What is the identity of this second product that you collected? How do you know? (HINT: You will find the table at