Domain: Natural Science — Chemistry
Target concept: Yellow precipitate formed in the haloform reaction

Video generation prompt: Add 1 mL of 0.1 M acetone solution to 2 mL of 0.1 M iodine in NaOH solution, and let it stand at room temperature for 5 minutes.

Evaluation guide:
(i) Target concept: Haloform reaction of methyl ketone (acetone) with iodine under alkaline conditions yields insoluble yellow iodoform precipitate.
Minimum mechanism: Iodine must be present as hypoiodite (OI⁻) in NaOH; acetone must be oxidized to carboxylate while releasing CHI₃; CHI₃ must be insoluble and yellow under aqueous conditions; no competing reduction or side reactions (e.g., no iodide accumulation causing brown color).
(ii)Storyline: [Frame 0–2] Two distinct liquids shown side-by-side: colorless acetone solution in small vessel, brownish-yellow iodine-in-NaOH in larger test tube. [Frame 3–5] Dropper approaches and delivers liquid from small vessel into large test tube; continuous motion, no cut. [Frame 6–8] Mixture remains static; no stirring or agitation. [Frame 9–10] Yellow granular precipitate visibly present at bottom; supernatant noticeably lighter than initial iodine solution. All events occur in fixed frontal view; container never leaves frame; lighting and perspective remain constant; precipitate must appear *only after* addition + stillness, never during or before.

Manual:
Experimental Procedure
1. Place 2 mL of iodine-in-NaOH solution in a clear test tube.
2. Add 1 mL of acetone solution using a dropper/pipette.
3. Let stand undisturbed for 5 minutes at room temperature.
Observation of Experimental Phenomena
A bright yellow precipitate forms and settles at the bottom; the supernatant becomes pale yellow or nearly colorless.
Summary of Experimental Principles
Acetone undergoes haloform reaction with iodine in basic medium, producing iodoform (CHI₃) — a characteristic yellow crystalline solid insoluble in water.

Prompt Grounding rubric:
level_1: No acetone solution, no iodine-in-NaOH solution, no container shown, or no addition action depicted; objects are unidentifiable or replaced with unrelated items (e.g., water instead of iodine solution, beaker instead of test tube).
level_2: At least one correct object is present (e.g., a liquid in a container), but the critical pair (acetone solution and iodine-in-NaOH solution) is missing or mislabeled; addition action is absent or performed on wrong objects; container type is incorrect (e.g., flask shown when test tube required).
level_3: Both acetone solution and iodine-in-NaOH solution are visually present in separate containers; addition action occurs (liquid transfer from one container to another); container is a clear vertical vessel (e.g., test tube or small cylinder); volumes are implied as unequal (smaller volume added to larger volume); no spatial violation (e.g., no floating liquids, no teleportation between shots).
level_4: All elements of 3-score are satisfied, AND the addition is clearly from a smaller-volume source (representing 1 mL) into a larger-volume recipient (representing 2 mL); both solutions are in the same frame before and during addition; no cut or jump disrupts the continuity of the addition event; container remains fixed in viewpoint throughout.
level_5: All elements of 4-score are satisfied, AND the two solutions are distinguishable by color *before* mixing: iodine-in-NaOH appears brownish-yellow (not pure brown or purple), acetone solution is colorless; the transfer tool (e.g., dropper or pipette) is visible and correctly used to deliver liquid *into* (not beside) the recipient; no occlusion, no motion blur obscuring the act of delivery, no duplicate or phantom objects.

Scientific and Causal Correctness rubric:
level_1: No yellow precipitate appears at any time; final mixture is uniformly colored (e.g., stays brown, turns black, or clears completely); no discernible solid formation; or precipitate appears *before* addition or *during* addition (i.e., violates temporal causality).
level_2: A precipitate forms but is not yellow (e.g., white, gray, orange, or green); or precipitate appears but lacks association with the mixture (e.g., forms on wall only, floats without settling, or appears in isolation without preceding addition); or color change of supernatant contradicts haloform reaction (e.g., deepens to black or fades to colorless without precipitate).
level_3: Yellow precipitate appears *after* addition and standing; it is granular or fine particulate (not amorphous film or oil layer); it settles at bottom or remains suspended as discrete particles; supernatant is visibly lighter than initial iodine-in-NaOH (e.g., pale yellow or near-colorless), confirming iodine consumption.
level_4: All elements of 3-score are satisfied, AND precipitate appears *only after* the addition is complete and a stillness period is visually implied (no agitation shown post-addition); no competing phenomena occur (e.g., bubbling, boiling, or color flash); supernatant clarity and precipitate color are consistent across the frame; no localized discoloration or chromatic inconsistency.
level_5: All elements of 4-score are satisfied, AND precipitate is exclusively *in the mixture*, not on container walls or meniscus; no dissolution or redispersion observed during stillness; yellow hue matches natural cadmium-yellow or mustard-yellow (not fluorescent, metallic, or desaturated); no co-occurring incorrect state changes (e.g., no solid-to-liquid transition, no unexpected transparency shift in precipitate).

Spatiotemporal Consistency rubric:
level_1: Severe spatiotemporal rupture: container changes position/orientation between shots without motion; liquid “teleports” from source to recipient; abrupt light/shadow shift mid-scene; container fractures or deforms unnaturally; frame cuts to unrelated scene.
level_2: Moderate rupture: container shifts laterally or rotates without visible cause; liquid surface jumps discontinuously (e.g., level changes instantly without flow); addition action shows no motion path (e.g., pipette tip appears already inside recipient); lighting flickers or casts inconsistent shadows across consecutive frames.
level_3: Minor but detectable discontinuities: brief motion blur obscures start/end of addition; slight jitter in camera or container; one frame shows partial occlusion of key action; lighting remains consistent but intensity varies slightly; no structural deformation or teleportation.
level_4: All elements of 3-score are satisfied, AND motion of liquid during addition is continuous and directionally coherent (no backtracking, no stuttering flow); container remains rigid and upright; no inter-frame warping or stretching of liquid surface; shadow position and softness remain stable across all frames.
level_5: All elements of 4-score are satisfied, AND motion is fluid and physically plausible: liquid stream maintains cohesive column during transfer; meniscus adjusts smoothly pre/post-addition; no frame duplication, no ghosting, no inter-frame misalignment of container edges or liquid interface; parallax and perspective remain fixed and geometrically self-consistent.