The melting point and boiling point for four solvents are given in the following table:

\[
\begin{tabular}{|c|c|c|}
\hline
Solvent & Melting Point [tex]$\left({ }^{\circ} C \right)$[/tex] & Boiling Point [tex]$\left({ }^{\circ} C \right)$[/tex] \\
\hline
methylene chloride & -96.7 & 39.8 \\
\hline
methanol & -97.9 & 64.7 \\
\hline
isopropyl alcohol & -89.0 & 82.2 \\
\hline
chlorobenzene & -45.0 & 132.1 \\
\hline
\end{tabular}
\]

Suppose a student measured a boiling point of [tex]$65.0^{\circ} C$[/tex] and a melting point of [tex]$-98.1^{\circ} C$[/tex] for an unknown liquid. What solvent did the student have as an unknown?

A. isopropyl alcohol
B. chlorobenzene
C. methanol
D. methylene chloride

To determine the identity of the unknown solvent based on its melting point and boiling point, we will compare the given data about the unknown solvent with the data from the table.

Here is the provided data for the solvents:
- methylene chloride: melting point = -96.7°C, boiling point = 39.8°C
- methanol: melting point = -97.9°C, boiling point = 64.7°C
- isopropyl alcohol: melting point = -89.0°C, boiling point = 82.2°C
- chlorobenzene: melting point = -45.0°C, boiling point = 132.1°C

The student measured the following properties for the unknown solvent:
- melting point: -98.1°C
- boiling point: 65.0°C

Now, let's compare the melting point and boiling point of the unknown solvent with those of the given solvents.

### Step-by-step Comparison:

1. methylene chloride:
- Melting point: -96.7°C (higher than -98.1°C)
- Boiling point: 39.8°C (lower than 65.0°C)
- Does not match both properties.

2. methanol:
- Melting point: -97.9°C (higher than -98.1°C but very close)
- Boiling point: 64.7°C (very close to 65.0°C)
- Matches almost exactly.

3. isopropyl alcohol:
- Melting point: -89.0°C (higher than -98.1°C)
- Boiling point: 82.2°C (higher than 65.0°C)
- Does not match both properties.

4. chlorobenzene:
- Melting point: -45.0°C (higher than -98.1°C)
- Boiling point: 132.1°C (higher than 65.0°C)
- Does not match both properties.

Based on these comparisons, the solvent that most closely matches the student’s measurements of -98.1°C for melting point and 65.0°C for boiling point is methanol.

So, the unknown solvent is methanol.