Domain: Healthcare — Nutrition and Food Hygiene
Target concept: Detection of Heavy Metal Mercury

Video generation prompt: A test tube containing 10 mL of food extract with excessive mercury ion concentration was treated with an appropriate amount of dithizone-chloroform solution. After shaking the tube and allowing it to stand, the scene was continuously photographed for several minutes.

Evaluation guide:
(i) Target concept: Visual detection of mercury contamination via selective chelation and phase-partitioning.
Minimum mechanism: Dithizone must be present in chloroform solvent; mercury ions must be in aqueous food extract; shaking enables interfacial contact and complex formation; standing enables phase separation driven by immiscibility and density difference; red-orange color must localize solely to the chloroform layer and must only appear after the shaking/standing reaction, not beforehand.
(ii)Storyline: [Frame 0-1] Static shot: upright test tube with clear food extract. -> [Frame 2] Dithizone-chloroform solution (green, its native unreacted color) added - visible as a separate layer or droplets. -> [Frame 3-4] Vigorous shaking: tube oscillates, liquids mix turbulently. -> [Frame 5] Immediate cessation: tube returns upright, no motion. -> [Frame 6-10] Standing phase: the mercury-dithizonate complex forms and a red-orange layer emerges, separating sharply at the interface - color confined to one liquid phase, stable and non-diffusing. All events occur from a fixed frontal viewpoint with consistent lighting and no occlusion.

Manual:
Experimental Procedure
1. Place a clean test tube containing 10 mL of colorless food extract.
2. Add dithizone-chloroform solution (green, its color before reacting with mercury) to the tube.
3. Cap and shake vigorously for ~2 seconds.
4. Place tube upright and let stand undisturbed for several seconds.
Observation of Experimental Phenomena
After shaking and standing, the green dithizone-chloroform layer turns a distinct red-orange color - localized exclusively in the chloroform phase - with sharp separation from the aqueous food extract layer.
Summary of Experimental Principles
Mercury ions (Hg2+) in food extract react with dithizone in chloroform to form a stable red-orange chelate complex, replacing the reagent's original green color. The complex partitions into the chloroform layer, enabling visual detection of excessive mercury.

Prompt Grounding rubric:
level_1: No test tube is shown; no food extract liquid appears; no dithizone-chloroform solution is added; neither a shaking motion nor a standing/settling phase is shown; or the clip does not hold a continuous view of the tube for several seconds.
level_2: At least a transparent tube-shaped container, some liquid, or a hand moving near a container appears, but the required test tube holding food extract, the dithizone-chloroform addition, and the shake-then-stand sequence are not all clearly present together.
level_3: A transparent test tube holding a clear or pale liquid (the food extract) is shown; a second liquid (the dithizone-chloroform solution) is added to it or sits adjacent before addition; a shaking action is depicted; a standing/stillness phase follows the shaking; all of this plays out in one continuous scene from a fixed viewpoint.
level_4: Everything required for score 3 holds, and in addition: the dithizone-chloroform solution reads as green - its correct native color - at the moment it is added, before any shaking occurs; the shaking clearly precedes the standing phase rather than the reverse; the test tube stays upright and undisturbed once standing begins; and no object enters or leaves the frame partway through the sequence.
level_5: Everything required for score 4 holds, and in addition: the test tube's proportions look like an ordinary laboratory test tube - narrow, several times taller than it is wide - rather than a distorted or oddly scaled prop; the food extract fills roughly the lower portion of the tube before the reagent is added; the green dithizone-chloroform solution is introduced as a distinct layer or as droplets rather than instantly blending in; the shaking motion is vigorous and visibly involves the whole tube moving, not just a slight wobble; and the settling into stillness after shaking is shown within the same unbroken shot.

Scientific and Causal Correctness rubric:
level_1: No color change ever appears in the tube; the liquid stays a single homogeneous, colorless mixture through shaking and standing; no separation into two visually distinct layers occurs at any point.
level_2: Some color shows up somewhere in the frame, but not inside the food-extract/dithizone-chloroform mixture itself; or a color appears before the dithizone-chloroform solution has been added or before shaking has happened; or the liquid separates into two layers without either layer taking on the red-orange color.
level_3: Once shaking stops and the tube stands, a red-orange color develops inside the tube's liquid contents; this colored layer is clearly liquid (not a solid residue or smear on the glass) and stands out against the tube's background; the color's appearance coincides with the standing phase rather than showing up during the shake itself, consistent with the mercury-dithizonate complex forming as the two phases settle.
level_4: Everything required for score 3 holds, and in addition: the red-orange color sits in only one of the two liquid layers (the chloroform phase) and never bleeds into the other, watery layer or spills outside the tube; once it appears, the color's intensity holds steady through the rest of the standing phase rather than fading or spreading across the interface.
level_5: Everything required for score 4 holds, and in addition: the red-orange layer is absent during shaking and appears only once the tube has come to rest, developing within the first few seconds of stillness; the boundary between the red-orange chloroform layer and the clear aqueous layer stays crisp rather than blurring together; and the hue stays a consistent red-orange rather than drifting toward purple, brown, or another shade.

Spatiotemporal Consistency rubric:
level_1: The test tube vanishes from view and reappears, or jumps to a different spot on the table between frames; the liquid inside changes level or volume with no shaking or pouring shown to explain it; the room's brightness swings sharply from one frame to the next with no cause; or the camera cuts or spins with no physical reason.
level_2: The tube stays in frame, but at least one of the following breaks the flow: the tube's position shifts between the shaking phase and the standing phase without a continuous motion connecting them; the liquid surface resets to a different height right after shaking ends with no visible cause; a highlight or glare on the glass swaps sides without the tube or light appearing to move; or the tube rotates more than roughly 30 degrees with no hand or shaking motion visible to cause it.
level_3: The test tube keeps the same position, tilt, and apparent size throughout the whole clip; the liquid's surface moves continuously while shaking and settles smoothly once the tube is still; the light source's direction and the strength of the shadow the tube casts on the table stay the same from the first frame to the last; and the tube's outline and the liquid inside it stay solid, without flickering or turning see-through.
level_4: Everything required for score 3 holds, and in addition: the shaking itself looks like smooth back-and-forth motion that gradually loses amplitude as the tube comes to rest, rather than jerking to a sudden stop; no frame repeats or skips ahead during the shake; and the tube's position relative to background objects on the table stays consistent, with no sliding or drifting of one relative to the other.
level_5: Everything required for score 4 holds, and in addition: the last swing of the shake finishes cleanly and the tube then holds completely still for several seconds with no further rocking; the liquid surface settles flat with no lingering ripple; and the tube and the table behind it stay in matching focus throughout, so neither one blurs while the other stays sharp.