Answer
The first molecule will be acidic, the second will be basic, the third will be a conjugate base, and the forth will be a conjugate acid.
Work Step by Step
The key part of the picture that distinguishes which will be acidic or basic is in the products part of the picture. We can interpret the picture into the reaction
1_______2_______3______4
$NH_{3} + NH_{3}$ -> $NH_{2}$$^{-}$ + $NH_{4}$$^{+}$
The molecule that donates the hydrogen ion, #1, is acidic, which fits with our Arrhenius definition of acids. Therefore, #2 has to be basic since it is the receptor of the hydrogen ion. When the reaction occurs, #3 will become a conjugate base as it was previously acidic and likewise #4 will become a conjugate acid as it was previously basic.
