Which of the following pairs of particle diagrams best represent two different phases of the same compound?

• A. One diagram shows closely packed particles in a fixed arrangement, and the other shows particles spaced farther apart and moving freely.
• B. Both diagrams show particles in a fixed, orderly arrangement.
• C. Both diagrams show particles randomly distributed and moving rapidly.
• D. One diagram shows particles of two different colors mixed together, and the other shows only one color.

Answer: (A)

Verified step by step guidance

1. Understand that different phases of the same compound correspond to different physical states, such as solid, liquid, or gas, which differ in particle arrangement and movement.
2. Recall that in a solid phase, particles are closely packed in a fixed, orderly arrangement and vibrate in place, while in a gas phase, particles are spaced far apart and move freely and rapidly.
3. Analyze the given options by comparing particle arrangement and movement: look for one diagram with closely packed, fixed particles (solid) and another with particles spaced farther apart and moving freely (gas or liquid).
4. Recognize that diagrams showing both phases with fixed, orderly arrangements represent the same phase (likely solid), and diagrams with both showing random, rapid movement represent the same phase (likely gas).
5. Conclude that the correct pair must show two different phases by depicting one diagram with fixed, closely packed particles and the other with particles spaced farther apart and moving freely, representing two physical states of the same compound.