Question

a student was observing a sweet food and a jar containing a sour food. the image above shows the sweet and sour foods. a certain amount of energy was transferred into both substances. the same amount of energy was utilized. the same amount of energy was transferred into both substances, but the food had changed phase while the other had not. which food changed phase, and how did it change?
a) the sweet food changed phase because the molecules were able to move fast enough to overcome the attraction between them. its molecules now move away from each other.
b) the sweet food changed because the strong attraction between molecules made their movement slower. its molecules now move around each other.
c) the sour food changed because the weak attraction between molecules let them move faster. its molecules now move away from each other.
d) the sour food changed because the molecules were able to move fast enough to overcome the attraction between them. its molecules now move in place.

Explanation:

To solve this, we analyze the phase change of the sweet food (likely a solid initially, then melting or softening) and the sour food (maybe a liquid or with molecules that can move). Let's evaluate each option:

• Option a: Says the sweet food changed because molecules moved fast to overcome attraction. But if it's sweet (like a solid candy), strong attractions hold molecules. If energy is added, molecules move faster to overcome attraction (melting). Wait, but the sour food didn’t change. Wait, maybe the sweet food was a solid, and energy (heat?) made its molecules move fast enough to overcome intermolecular attractions, causing it to change phase (e.g., melt). Let's check other options:
• Option b: Claims strong attraction made movement slower. But if the food changed, attraction was overcome, not causing slower movement. Eliminate.
• Option c: Talks about weak attraction letting molecules move faster. But sweet foods (like candy) have strong intermolecular forces (e.g., sugar crystals). Weak attraction is more for liquids/gases. Eliminate.
• Option d: Says sour food changed (but the problem states only one changed). Eliminate.

Wait, re-reading: "The same amount of energy was transferred into both substances. One substance (sweet) changed phase, the other (sour) did not." So the sweet food’s molecules needed enough energy (speed) to overcome attractions (like in melting a solid). So Option a makes sense: "The sweet food changed because the molecules were able to move fast enough to overcome the attraction between them. Its molecules now move away from each other."

Answer:

a. The sweet food changed because the molecules were able to move fast enough to overcome the attraction between them. Its molecules now move away from each other.