To determine which statement is correct about the freezing point of the unknown substance, let's carefully examine the given data table and understand the transitions between states of matter:
[tex]\[
\begin{tabular}{|c|c|c|}
\hline
\begin{tabular}{c}
Time \\
(minutes)
\end{tabular} & \begin{tabular}{c}
Temperature \\
(degrees Celsius)
\end{tabular} & State of matter \\
\hline
0 & 25 & Liquid \\
\hline
2 & 23 & Liquid \\
\hline
4 & 18 & \\
\hline
6 & 18 & \\
\hline
8 & 18 & Solid \\
\hline
10 & 15 & Solid \\
\hline
12 & 10 & \\
\hline
\end{tabular}
\][/tex]
1. Analyzing the Data Points:
- At 0 minutes, the temperature is 25°C and the substance is in a liquid state.
- At 2 minutes, the temperature is 23°C and the substance is still in a liquid state.
- At 4 minutes, the temperature is 18°C, but the state of matter is not given.
- At 6 minutes, the temperature remains 18°C, with the state of matter still not given.
- At 8 minutes, the temperature is 18°C and the substance has transitioned to a solid state.
- At 10 minutes, the temperature drops to 15°C and the substance remains a solid.
- At 12 minutes, the temperature further drops to 10°C, and the state is not specified.
2. Freezing Point Determination:
- The freezing point of a substance is the temperature at which it transitions from a liquid to a solid.
- Observing the data, at both 2 minutes (23°C) and 4 minutes (18°C), the state of matter at 23°C remains liquid.
- The transition from liquid to solid can be observed between the 2-minute mark (23°C) and the 8-minute mark (18°C).
3. Conclusion:
- Since the substance starts as a liquid and is observed as a solid at 18°C, we can conclude that it transitions from liquid to solid at 18°C.
Therefore, the correct statement is:
- Its freezing point is [tex]\( 18^{\circ} \text{C} \)[/tex].
