Step 1: Classification of Phenols Based on Hydroxyl Groups - Monohydric Phenol: Contains one \(-OH\) group (e.g., Phenol).
- Dihydric Phenol: Contains two \(-OH\) groups (e.g., Catechol).
- Trihydric Phenol: Contains three \(-OH\) groups (e.g., Pyrogallol).
Step 2: Structural Formulas

Arrange the following compounds in increasing order of their boiling points:

The reaction 
suggests that phenol is :
In the reaction R–OH + HCl $\xrightarrow{\text{ZnCl}_2}$ RCl + H$_2$O, what is the correct order of reactivity of alcohols?