\begin{tabular}{|l|}\hline Question 7 \\ Which statement best describes the motion \\ of the molecules of a solid object? \\ O They vibrate within a fixed volume. \\ \( \begin{array}{l}\text { They move around freely within a fixed } \\ \text { volume. } \\ \text { They vibrate in place and take the shape of a } \\ \text { container. } \\ \text { They move around freely and take the shape } \\ \text { of a container. }\end{array} \) \\ \hline\end{tabular}

The correct statement that best describes the motion of the molecules in a **solid** object is: **They vibrate within a fixed volume.** ### Explanation: - **Fixed Volume and Shape:** In a solid, molecules are closely packed in a fixed arrangement. This structure gives solids their definite shape and volume. - **Molecular Motion:** The molecules in a solid primarily vibrate about their fixed positions. Unlike liquids and gases, the molecules do not move freely or take the shape of their container. ### Review of Other Options: 1. **They vibrate within a fixed volume.** - **Correct for solids.** 2. **They move around freely within a fixed volume.** - **Describes liquid behavior**, where molecules can flow but the volume remains constant. 3. **They vibrate in place and take the shape of a container.** - **Describes liquid behavior**, where molecules vibrate and can move to take the container's shape. 4. **They move around freely and take the shape of a container.** - **Describes gas behavior**, where molecules move freely and expand to fill the container. **Answer:** They vibrate within a fixed volume.