Domain: Natural Science — Chemistry
Target concept: Alkyne solutions decolorize bromine water (electrophilic addition reaction)

Video generation prompt: Two transparent test tubes containing orange bromine water; add a clear alkyne solution to the left tube and an equal volume of an inert, water-miscible diluent (such as distilled water) to the right tube, then shake them gently side by side.

Evaluation guide:
(i) Target concept: Visual demonstration of selective chemical reactivity via differential decolorization of bromine water.
Minimum mechanism: Bromine water must be orange due to dissolved Br₂; the alkyne must contain at least one C≡C bond to react stoichiometrically with Br₂; the diluent added to the control tube must be water-miscible (so it blends fully into the bromine water rather than forming a separate layer), chemically non-reactive toward Br₂ (e.g., distilled water), and optically clear; the reaction must proceed rapidly under mild agitation to yield colorless dibromoalkene/dibromide products.
(ii)Storyline: Frame 0–1: Static side-by-side view of two tubes filled with uniform orange liquid. Frame 2–3: Clear liquid dispensed separately into left (alkyne) and right (diluent) tubes, with visually identical delivery. Frame 4–5: Both tubes begin synchronous gentle vertical oscillation. Frame 6–7: During shaking, left tube's orange hue progressively vanishes until fully colorless; right tube retains identical orange saturation and uniformity throughout, mixing smoothly with no separate layer forming. Frame 8–9: Final still frame confirms left tube transparent/clear, right tube unchanged orange; no motion, no ambiguity. Perspective: Fixed frontal close-up, full tube height visible, no camera movement or angle shift.

Manual:
Experimental Procedure
1. Place two identical transparent test tubes side-by-side.
2. Fill both with an equal volume of orange bromine water.
3. Add clear alkyne solution to the left tube; add an equal volume of an inert, water-miscible diluent (e.g., distilled water) to the right tube.
4. Gently shake both tubes simultaneously for ~2 seconds.
Observation of Experimental Phenomena
Left tube: orange color completely disappears, becoming colorless/clear.
Right tube: orange color remains unchanged throughout, mixing smoothly with no separate layer forming.
Summary of Experimental Principles
Alkynes undergo electrophilic addition with bromine, consuming Br₂ and decolorizing bromine water; a water-miscible inert diluent has no reactive π-bonds and blends homogeneously with the bromine water, so it causes no reaction and no phase separation.

Prompt Grounding rubric:
level_1: No two test tubes are shown, or the tubes are not transparent, or no orange bromine water is present in either tube, or nothing is added to the left tube, or nothing is added to the right tube, or the tubes are not arranged next to each other, or no shaking motion is shown.
level_2: Two transparent test tubes with orange bromine water sit next to each other, but at least one setup step is missing or wrong: the alkyne is not visibly added to the left tube only, the diluent is not visibly added to the right tube only, or neither tube is shaken after the additions.
level_3: Two transparent test tubes of orange bromine water are shown side by side; a clear liquid (the alkyne) is added only to the left tube and a clear liquid (the water diluent) is added only to the right tube; both tubes are then shaken gently; the alkyne and diluent are not swapped between tubes and shaking is not omitted from either tube.
level_4: Everything required for score 3 is shown, and in addition: the alkyne and the diluent look like the same clear, colorless, similar-viscosity liquid when added (so no visual hint reveals which tube received which reagent); both tubes are shaken with matching timing and motion; neither tube tips, rotates out of upright orientation, or leaves the frame while being shaken.
level_5: Everything required for score 4 is shown, and in addition: both tubes show the same liquid level before and after each addition (no overflow, no visibly mismatched fill height); nothing (glare, blur, a hand, or other object) blocks the view of either tube's contents at any point; the camera stays frontal and static, keeping the full height of both tubes in frame throughout.

Scientific and Causal Correctness rubric:
level_1: Neither tube changes color; or both tubes decolorize; or the left (alkyne) tube stays orange while the right (diluent) tube decolorizes; or a color change happens before the diluent/alkyne is added or before shaking begins; or either tube starts a color other than orange.
level_2: The left tube fades from orange toward colorless, but the right tube also visibly changes (paler orange, cloudy, or a different hue); or the left tube's color change happens without shaking; or the fade in the left tube is uneven (e.g., clear at the top, still orange at the bottom) without ever finishing.
level_3: During or right after shaking, the left tube goes fully from orange to colorless; the right tube stays evenly orange the whole time, with no fading, clouding, or hue shift; the color loss is limited to the left tube and tracks with the shaking.
level_4: Everything required for score 3 holds, and in addition: the left tube's decolorization is complete, with no leftover orange tint or a lingering orange band; the right tube shows no detectable change in its orange color or brightness at any frame; neither tube produces bubbles, cloudiness, or a separate floating layer, outcomes that would be inconsistent with a homogeneous alkyne/bromine-water reaction and a water-miscible diluent that mixes in fully.
level_5: Everything required for score 4 holds, and in addition: the left tube's fade from orange to colorless plays out over the span of the shaking, without lingering afterward or finishing before shaking starts; the right tube's orange color and clarity after shaking still look the same as the left tube looked immediately before it started fading; the color contrast between the two tubes is not caused by a lighting change or camera color shift.

Spatiotemporal Consistency rubric:
level_1: One tube vanishes from the shot or pops back into frame between cuts; liquid sprays out of a tube or disappears from inside it; the lighting changes suddenly enough to throw off the color comparison; or a tube visibly cracks or its cap flies off.
level_2: A tube shifts sideways by more than roughly a tenth of its height between key frames; the shaking has two or more sudden stop-start jumps instead of continuous motion; a shadow jumps to a different position without the light source moving; or the background flickers or warps.
level_3: Both tubes stay in the same relative spot and orientation throughout; the shaking motion is smooth and continuous within each tube; the lighting stays even across the whole clip; neither tube bends, stretches, or gets clipped by the frame edge; neither tube flickers or is blocked from view between frames.
level_4: Everything required for score 3 holds, and in addition: both tubes move with matching amplitude, speed, and direction while being shaken (neither swings more than the other); the liquid surface inside each tube moves the way a real meniscus would (sloshing, not sliding as a rigid block); the two tubes don't shift relative to each other in a way that would suggest the camera itself moved.
level_5: Everything required for score 4 holds, and in addition: the two tubes' shaking motion looks mirrored and repeatable rather than random; no motion blur ever hides the liquid's color or the liquid-air boundary; the focus and the apparent size/perspective of both tubes stay constant, consistent with a fixed frontal camera.