Domain: Healthcare — Nutrition and Food Hygiene
Target concept: Sulfite Detection

Video generation prompt: A 10-mL aliquot of the preserved fruit extract containing sulfite was placed in a test tube, to which a solution of acid pararosaniline reagent was added. The mixture was thoroughly shaken and allowed to stand. A photograph was taken continuously with the camera aligned with the test tube.

Evaluation guide:
(i) Target concept: Visual confirmation of sulfite presence via chromogenic reaction in a controlled, observable assay.
Minimum mechanism: Sulfite must be present in extract; acid pararosaniline must be chemically intact; reaction requires acidic pH and time post-mixing to develop; color formation is intrinsically tied to molecular coupling, not dilution or lighting.
(ii)Storyline: [Phase 1] Static setup: empty test tube centered in fixed frontal view. [Phase 2] Aliquot delivery: 10-mL liquid enters tube, filling ~1/3–1/2 height. [Phase 3] Reagent addition: second liquid stream enters same tube, mixing visibly. [Phase 4] Agitation: tube oscillates smoothly ~3–5 cycles. [Phase 5] Stillness: tube held rigidly upright; liquid settles; magenta color emerges uniformly within column over ~2–4 sec equivalent. [Phase 6] Capture: brief brightness pulse or shutter cue while color is fully developed. All phases maintain fixed viewpoint, full tube visibility, and no occlusion.

Manual:
Experimental Procedure
1. A 10-mL aliquot of preserved fruit extract is placed into a clear vertical test tube.
2. Acid pararosaniline reagent is added to the tube.
3. Tube is shaken thoroughly and then held motionless.
Observation of Experimental Phenomena
A uniform magenta-to-purple color develops exclusively within the liquid column during stillness — absent before reagent addition and absent during shaking.
Summary of Experimental Principles
Sulfite in the fruit extract reacts with acidified pararosaniline to form a stable magenta-colored pararosaniline-methylsulfonic acid addition compound (not a diazonium salt — diazonium chemistry instead requires an aromatic amine reacting with nitrous acid, an unrelated pathway); color intensity correlates with sulfite concentration.

Prompt Grounding rubric:
level_1: No test tube, no preserved fruit extract, and no acid pararosaniline reagent are visible anywhere in the shot, and none of the three actions described in the prompt (pouring the extract, adding the reagent, or shaking/standing the tube) takes place.
level_2: At least one of the tube, the fruit extract, or the reagent bottle is visible, but the 10-mL aliquot is never poured into the tube, the reagent is never added, and the camera is not held in a fixed, tube-aligned framing.
level_3: A test tube holding a pale, clear-to-yellowish liquid (the preserved fruit extract) sits centered in a fixed, tube-aligned shot; a measured pour delivers roughly a 10-mL aliquot into the tube; a second pour adds the acid pararosaniline reagent into the same tube; the camera keeps this same framing throughout, but the video stops short of showing any shaking or standing phase.
level_4: Everything required for score 3 holds, and in addition the tube is visibly shaken with a back-and-forth motion for a few cycles, followed by a period where it is held completely still; the tube, extract, and reagent all stay within frame for the whole sequence and keep the same relative sizes and positions to one another.
level_5: Everything required for score 4 holds, and in addition the steps occur in the correct order (aliquot poured in, reagent added, tube shaken, tube held still, then a shutter-click or brightness-pulse cue marking the photograph), with nothing else entering the frame and the tube staying centered and fully visible in the same fixed framing from the first step to the last.

Scientific and Causal Correctness rubric:
level_1: The liquid in the tube never changes color at all after the reagent is added, or it turns some color inconsistent with a sulfite-pararosaniline reaction (e.g., blue, green, or black) instead of the expected magenta/purple, with no visible connection between adding the reagent and any color change.
level_2: Some magenta or purple color is visible in the shot (e.g., on the reagent bottle's label or in the background) but the liquid inside the tube itself never takes on this color after mixing, or a color appears in the tube before the reagent is even added, or the color is visible only during shaking and disappears the instant the tube goes still.
level_3: After the reagent is added and once the tube goes still, the liquid inside the tube itself develops a magenta-to-purple color that was not present beforehand (neither during the aliquot pour nor at reagent addition); the hue reads as one consistent band of color across the liquid column rather than scattered flecks or a colorless liquid with a colored surface film.
level_4: Everything required for score 3 holds, and in addition the color only begins to appear once the shaking has stopped and stillness begins (the liquid stays uncolored, or only faintly tinted, throughout the shaking itself); once it appears, the magenta-to-purple hue holds steady rather than fading in and out; and no second, conflicting color (e.g., a yellow streak alongside the magenta) shows up in the same liquid at the same time.
level_5: Everything required for score 4 holds, and in addition the magenta-to-purple color fills the entire liquid column evenly, with no layering, ring, or meniscus-only tinting; once fully developed, the color's intensity holds steady rather than continuing to deepen or fade for the rest of the clip; nothing else in the shot (glare, a colored label, an overlay) could be mistaken for this color change; and the color reads purely as the product of the extract–reagent reaction rather than any external source.

Spatiotemporal Consistency rubric:
level_1: The test tube vanishes from view partway through the clip and then pops back into frame later, or the liquid inside jumps between two completely different fill levels with no visible pour connecting them; the camera cuts to a different angle mid-sequence; or the tube visibly bends, rotates more than about 30° off its vertical axis, or passes through the bench without anything touching it.
level_2: The tube's position on the bench drifts sideways or up/down by more than about a third of its height between the mixing and stillness phases; the liquid column's height changes without a corresponding pour of the 10-mL aliquot or the reagent; the shaking motion freezes and then jumps ahead instead of moving continuously; or the tube shows visible tremor or drift during the stillness phase that should show no motion at all.
level_3: The tube stays in the same spot on the bench at the same vertical orientation from the moment the aliquot is poured to the final still frame; the liquid's top surface stays flat and horizontal once shaking ends; the shaking itself is a smooth, repeating back-and-forth motion with no stutter; and nothing outside the tube (e.g., the reagent bottle or the countertop behind it) unexpectedly enters or leaves the shot.
level_4: Everything required for score 3 holds, and in addition the camera's framing of the tube never shifts, zooms, or pans at any point in the sequence; the liquid's meniscus stays smooth and intact with no splashing, foaming, or bubbling introduced by the shaking; and the reagent bottle or any other prop visible beside the tube keeps the same size and position relative to the tube throughout.
level_5: Everything required for score 4 holds, and in addition the motion between frames is smooth with no strobing, warping, or ghosting of the tube or liquid; the shaking phase and the stillness phase each last a plausible, unrushed duration relative to one another (neither is compressed or stretched oddly); the tube's glass wall keeps a constant thickness and curvature throughout; and any glare or reflection on the tube's glass or on the reagent bottle beside it stays fixed at the same spot rather than sliding as if the light source itself were moving.