imagine each of the molecules shown below was found in an aqueous solution. can you tell whether the…

Explanation:

Step1: Analyze first molecule

It has an amino - group ($\ce{-NH2}$) which can accept a proton (basic) and a carboxylate - group ($\ce{-COO-}$) which is the conjugate base of a carboxylic acid. Also, the phenolic $\ce{-OH}$ can donate a proton. Overall, the phenolic $\ce{-OH}$ and the acidic nature of the amino - acid part (due to the carboxyl group in its conjugate base form) make it acidic.

Step2: Analyze second molecule

It has an amino - group ($\ce{-NH3+}$) which is a weak acid (can donate a proton) and a carboxyl - group ($\ce{-COOH}$) which is an acid. The presence of the $\ce{-OH}$ group on the side - chain also has some acidic character. Overall, it is acidic.

Step3: Analyze third molecule

It has an amino - group ($\ce{-NH3+}$) which is acidic and a carboxylate - group ($\ce{-COO-}$) which is basic. In the zwitterionic form, the positive and negative charges balance out to some extent, but considering the nature of amino - acids and their behavior in solution, the amino - acid is amphoteric. However, in most physiological conditions, the overall charge and behavior make it acidic due to the ability of the $\ce{-NH3+}$ to donate a proton more readily in some cases.

Step4: Analyze fourth molecule

It has an amino - group ($\ce{-NH3+}$) which is acidic and a carboxyl - group ($\ce{-COOH}$) which is acidic. The overall molecule is acidic.

Answer:

1. acidic
2. acidic
3. acidic
4. acidic