Which of the following best describes how to modify the structure of a base to draw its conjugate acid?

• A. Replace an oxygen atom with a nitrogen atom.
• B. Add a proton ($H^{+}$) to the base at the site of highest electron density.
• C. Remove a proton ($H^{+}$) from the base.
• D. Add a hydroxide ion (${\mathrm{OH}}_{-}$) to the base.

Answer: (B)

Verified step by step guidance

1. Understand that a conjugate acid is formed when a base gains a proton (H\textsuperscript{+}).
2. Identify the site of highest electron density on the base, as this is where the proton will most likely attach.
3. Modify the structure of the base by adding a proton (H\textsuperscript{+}) to this site, increasing its positive charge.
4. Recognize that replacing atoms or removing protons does not correctly represent the formation of a conjugate acid from a base.
5. Confirm that adding a hydroxide ion (OH\textsuperscript{–}) is not relevant to forming a conjugate acid, as it would instead make the species more basic.