**Category:** Organic Chemistry  
**Subtype:** Chemical Reactions, Stoichiometry  

**Problem Overview:**  
This problem involves a mixture (X) containing a saturated alcohol (single functional group) and an ester. The mixture is subjected to combustion, and the stoichiometry of the reaction is analyzed. Specifically, the problem provides the mass of the mixture and the amount of potassium hydroxide (KOH) that reacts with it, leading to the formation of a salt and two alcohols. Additionally, the problem involves the reaction of sodium (Na) with the alcohol, producing hydrogen gas (H₂), and requires calculating the mass percentage of the alcohol in the mixture.

**Key Points to Solve the Problem:**  
- Determine the moles of KOH and the resulting products.
- Use the reaction with Na to find the moles of alcohol.
- Calculate the mass of the alcohol and then find its percentage in the mixture X.