Domain: Natural Science — Chemistry
Target concept: The solution gradually changes from pale yellow to colorless, with no precipitate or gas formed, and the system remains clear.

Video generation prompt: Add the periodic acid reagent to an ethylene glycol solution, mix thoroughly, then allow it to stand, and observe the changes in the solution's appearance.

Evaluation guide:
(i) Target concept: Oxidation of vicinal diols by periodic acid proceeds via cleavage to carbonyl compounds, with iodine(VII) reduced to iodine(V); the reaction mixture remains homogeneous and colorless upon completion because H5IO6 (or derivatives) and products (e.g., formaldehyde, formic acid) are all colorless and soluble in water.
Minimum mechanism: The reagent's initial pale-yellow tint comes from a small amount of lower-oxidation-state iodine species (e.g., trace I₂/HOI) held in fast equilibrium with the periodate in solution; as periodate oxidizes the ethylene glycol and is itself reduced toward colorless iodate (IO₃⁻), this equilibrium shifts and the color-bearing species are consumed as well, so the visible fade tracks the underlying oxidation rather than being an unrelated side effect; the system must remain kinetically stable against precipitation (no pH shift-induced hydrolysis) and thermodynamically stable against gas evolution (no CO2 or aldehyde decomposition under mild conditions).
(ii)Storyline: Frame 1–2: Two distinct containers visible: one holding pale yellow liquid (periodic acid reagent), one holding colorless liquid (ethylene glycol solution). Frame 3–4: Reagent is transferred into glycol container (pouring/swirling action). Frame 5–7: Uniform mixing motion (swirling or gentle inversion) results in homogeneous pale yellow solution. Frame 8–10: Solution sits motionless; color fades globally and continuously from pale yellow to colorless while retaining a sharp meniscus, uniform brightness, and no visible particulates. All observed from a fixed frontal viewpoint with consistent lighting and no occlusion.

Manual:
Experimental Procedure
1. Place a clear container with ethylene glycol solution.
2. Add periodic acid reagent to it.
3. Mix thoroughly.
4. Allow mixture to stand undisturbed.
Observation of Experimental Phenomena
The solution gradually changes from pale yellow to colorless; remains fully clear; no precipitate or gas forms.
Summary of Experimental Principles
Periodic acid oxidizes ethylene glycol, consuming the colored species; the reaction proceeds in solution without forming solids or gases, yielding a colorless, transparent product mixture.

Prompt Grounding rubric:
level_1: No periodic acid reagent container, no ethylene glycol solution container, no mixing action, and no standing phase appear; none of the required setup elements from the prompt are shown.
level_2: At least one relevant object appears (e.g., some container with liquid), but the periodic acid reagent and the ethylene glycol solution are not both clearly identifiable, and neither the mixing action nor the standing phase is shown.
level_3: Both the periodic acid reagent and the ethylene glycol solution are shown in distinguishable containers; the two are combined (poured or stirred together); and a standing phase follows (no further manipulation for a visible stretch before the final observation); all three steps appear in the right order, but the two starting liquids look nearly identical in color or viscosity with nothing to tell them apart.
level_4: The periodic acid reagent, the ethylene glycol solution, the mixing action, and the final combined solution are all visually distinct and clearly connected to each other; the mixing (pouring or swirling) is clearly shown; the standing phase is unambiguous (all motion stops, no further additions); the final solution sits in the same container used for mixing, with only a small, non-core flaw such as a brief flicker as the shot settles into the standing phase or a slight focus shift during observation.
level_5: Every object is easy to identify at a glance (a clearly distinct periodic acid container, a clearly distinct ethylene glycol container); the reagent is poured into the glycol solution as a visible stream, followed by clear swirling to mix; the mixture then sits undisturbed with no motion or lighting change during standing; the final solution stays fully in frame and continuously visible for the whole observation period.

Scientific and Causal Correctness rubric:
level_1: The final solution shows a precipitate, bubbling or fizzing, cloudiness, a color other than colorless (still yellow, or a new color like pink or brown), or the liquid appears to vanish; any of these breaks the core phenomenon, and there is no visible connection between mixing and any of these outcomes.
level_2: The solution starts pale yellow but never becomes colorless; or it becomes colorless but develops cloudiness, visible particles, or surface bubbles; or the color change happens without the mixing step ever being shown.
level_3: The solution starts pale yellow and ends colorless; no precipitate or gas is visible at any point; the solution stays optically clear throughout with no haze or particles; the mixing step comes before the color fade, but the fade itself looks abrupt (jumping straight from yellow to colorless with no visible gradual transition) or only part of the visible liquid actually changes color.
level_4: The solution starts a uniform pale yellow and fades to colorless in a way that looks continuous rather than a sudden jump; it stays fully clear and see-through the whole time with no cloudy patches or separation; no bubbles, crystals, or film appear before, during, or after standing, with only one small, non-core flaw, such as a brief reflection making the color momentarily hard to judge in one shot.
level_5: The color fade is smooth and even across the whole visible solution, never reversing or fading unevenly in patches; the liquid stays completely clear with no visible particles or bubbles anywhere; there is no glare or lighting artifact that would make it hard to judge the color or clarity; the fade begins soon after mixing and finishes sometime during the standing period, with no precipitate or gas appearing at any point.

Spatiotemporal Consistency rubric:
level_1: The container jumps to a different position or size between shots with no motion connecting them; the liquid disappears and reappears; the lighting switches abruptly between very different brightness levels with no visible cause; the container's shape warps or breaks; or the mixing motion reverses direction instantly with no slowdown.
level_2: Several moderate breaks occur together: the shot cuts abruptly more than once where continuous motion should be shown; the shadow on the container changes direction between shots with nothing to explain it; the container shifts position or rotates with no physical cause; or the liquid's surface wobbles unnaturally while the container is supposed to be sitting still.
level_3: One small spatiotemporal flaw is visible, such as a brief stutter during the mixing motion, a short lens flare that briefly obscures the solution, or a slight mismatch in how the container lines up with the background, but overall the container stays in the same place, the lighting stays steady, and the liquid settles naturally into stillness after mixing with no warping of the container.
level_4: The pour and mix are shown as one continuous, physically connected motion from source to target; the swirling motion settles smoothly into stillness; the container and liquid surface show no unexplained distortion; the lighting stays the same brightness and direction throughout; the only flaw is something small and non-core, such as a faint tremor in the frame during the standing phase that a viewer would only notice if looking for it.
level_5: The container stays visibly still and in the same place throughout the standing phase, with no vibration, ripple, or shimmer on the liquid surface; the pour follows a natural gravity-driven arc and the swirl gradually slows to a stop; the lighting, focus, and framing stay constant the whole time, with no flicker or drift; the whole sequence looks like an uninterrupted, steady recording.