Question

(01.04 hc)
the diagram shows the layers formed when 10 ml each of milk, soap water, and oil were slowly poured into a glass cylinder.
diagram: cylinder with layers labeled oil (top), soap water (middle), milk (bottom)
a plastic bead released gently into the cylinder settles on the layer separating the oil and soap water. what best compares the densities of the substances?

○ milk is denser than soap water, but the oil and the plastic bead are denser than milk.
○ milk is denser than the other liquids in the cylinder but not as dense as the bead.
○ the plastic bead is denser than oil, but milk and soap water are denser than the plastic bead.
○ the plastic bead is denser than soap water and milk, but oil is denser than the plastic bead.

Explanation:

1. Analyze the layering: In a cylinder, denser liquids settle at the bottom. So, from bottom to top: Milk (bottom) > Soap Water > Oil (top). This means \( \text{Density of Milk} > \text{Density of Soap Water} > \text{Density of Oil} \).
2. Analyze the plastic bead's position: The bead settles on the layer between oil and soap water. So, the bead is denser than oil (since it sinks through oil to the soap water - oil interface) but less dense than soap water (and thus also less dense than milk, as milk is denser than soap water) because it doesn't sink through soap water to milk.
3. Evaluate each option:

• Option 1: Milk is denser than soap water (correct), but oil and bead denser than milk? Oil is less dense than soap water and milk, and bead is less dense than soap water/milk (since it's at oil - soap water interface, not sinking to milk). So incorrect.
• Option 2: Milk denser than other liquids? Soap water is less dense than milk, oil is less dense than soap water, so milk is denser than other liquids (correct). But is milk less dense than the bead? The bead is at oil - soap water interface, so bead is less dense than soap water (and milk). So milk is denser than the bead? No, this option says milk is not as dense as the bead, which is wrong.
• Option 3: Bead denser than oil (correct, as it sinks through oil). Milk and soap water denser than bead (correct, as bead doesn't sink through soap water to milk, so soap water (and milk) are denser than bead). This matches our analysis.
• Option 4: Bead denser than soap water and milk? No, bead is at oil - soap water interface, so it's less dense than soap water (and milk). Oil denser than bead? No, bead sinks through oil, so bead is denser than oil. So incorrect.

Answer:

C. The plastic bead is denser than oil, but milk and soap water are denser than the plastic bead.