Domain: Natural Science — Chemistry
Target concept: The solution became completely clear, with no layering or precipitation, and ethylene glycol was formed.

Video generation prompt: Ethylene oxide is introduced into dilute sulfuric acid, and the mixture is gently shaken to observe the homogeneity of the solution.

Evaluation guide:
(i) Target concept: Acid-catalyzed ring-opening hydrolysis of ethylene oxide to yield ethylene glycol in aqueous medium.
Minimum mechanism: Ethylene oxide must be delivered as a gas (not a liquid) so it doesn't just add bulk solvent; dilute sulfuric acid supplies H⁺ to protonate the epoxide oxygen, letting water attack the strained ring; because sulfate/bisulfate is a poor nucleophile (unlike chloride), water wins the competition cleanly, so the only product is ethylene glycol, which is fully miscible and non-volatile, giving a stable, single-phase solution.
(ii) Storyline: Frame 0-1: Static shot of a labeled container holding dilute sulfuric acid (clear, colorless liquid, meniscus visible). Frame 2-3: Ethylene oxide gas is introduced via a visible inlet (no liquid stream, no bubbling artifact). Frame 4-5: Gas introduction stops; the container sits still for about one beat. Frame 6-8: Gentle, rhythmic side-to-side shaking begins and continues for at least two full back-and-forth cycles. Frame 9-10: Shaking stops; the final still frame shows an undisturbed, optically uniform solution surface -- no leftover motion blur, no distortion at the liquid's edge, no visible particles. All of this happens from one fixed frontal viewpoint; the container never leaves the frame; the lighting and background stay the same throughout.

Manual:
1. Experimental operation procedure: A gas inlet tube delivers ethylene oxide into a transparent container holding dilute sulfuric acid; immediately after introduction, the container is gently shaken by hand for about 2 seconds.
2. Observation of experimental phenomena: The solution stays completely clear, with no layering, cloudiness, or precipitation at any point; it looks like a single, uniform, colorless liquid before, during, and after shaking.
3. Summary of experimental principles: Ethylene oxide reacts with dilute sulfuric acid to form ethylene glycol, a water-miscible diol. Because the sulfate/bisulfate anion is a poor nucleophile, it does not compete with water for the protonated epoxide the way a halide such as chloride could, so the reaction proceeds cleanly to glycol without a competing chlorohydrin-type byproduct -- resulting in a stable, optically uniform aqueous solution.

Prompt Grounding rubric:
level_1: No ethylene oxide gas inlet is shown, no container of dilute sulfuric acid appears, no shaking motion happens, no liquid-holding container is visible at all, or the clip shows something unrelated (e.g., solids being mixed, a flame, or an unrelated lab setup).
level_2: One correct object shows up (e.g., a labeled bottle or a transparent container), but the ethylene oxide is missing or shown wrong (e.g., poured in as a liquid stream instead of introduced as gas through an inlet), the sulfuric acid container is missing or unlabeled, the shaking motion is missing or replaced by stirring or pouring, and there's no sense of checking whether the solution stays uniform.
level_3: A gas inlet (tube or labeled cylinder) is clearly shown introducing gas toward a transparent container holding dilute sulfuric acid; the container stays in place before and during the gas introduction; a gentle shaking motion (by hand or by a mechanical rig) is shown afterward; the liquid stays in the same container the whole time.
level_4: Everything in score 3 is present, and in addition the shaking only starts after the gas introduction is finished (not before or overlapping it), the container is clearly the same object before, during, and after, and there are no extra actions like pouring, heating, or adding other reagents.
level_5: Everything in score 4 is present, and in addition the gas introduction is visually distinct from any liquid addition (e.g., shown as a thin gas stream or a labeled inlet port, never as droplets or a pour), the shaking begins only once gas introduction has clearly ended and continues for at least two full back-and-forth swings, and the container keeps consistent labeling (e.g., 'dil. H2SO4') and unambiguous single-container containment the whole time.

Scientific and Causal Correctness rubric:
level_1: The solution shows layering, cloudiness, precipitate, a color change, or splits into separate phases at any point; or the outcome is shown as something other than a clear, single-phase liquid -- e.g., crystals forming, the liquid thickening noticeably, or visible heat/steam suggesting a different reaction.
level_2: The solution looks non-uniform at some point -- a visible break in the liquid surface, floating droplets, suspended flecks, or a hazy patch in part of the container -- or the final state shows cloudiness, settled material, or a separate layer; or the solution's state is never actually shown (e.g., the view stays on an empty container or is blocked).
level_3: The solution looks fully uniform (no visible boundaries, floating bits, or gradient) during and after shaking; there's no layering or precipitate; the end state matches the expected outcome: a clear, colorless, single-phase liquid consistent with the dissolved ethylene glycol product.
level_4: Everything in score 3 is present, and in addition the uniform appearance holds continuously from the first frame after shaking begins all the way to the end -- no passing haze, streak, or settling shows up partway through -- and there's no color shift (no yellowing, no pink tint) and no sudden change in how clear the liquid looks.
level_5: Everything in score 4 is present, and in addition there's no visual sign at all of incomplete mixing: no wavy distortion at the liquid's edge, no faint scattering halo anywhere in the liquid, no odd meniscus behavior at the container wall, and no lingering tiny droplets -- the solution looks just as uniform and clear as plain water or the starting dilute acid.

Spatiotemporal Consistency rubric:
level_1: The container jumps to a different spot or size between frames; the lighting suddenly switches character (a flash, a shadow that jumps to the opposite side, or the whole scene suddenly getting brighter or darker); the shaking motion skips or reverses direction unnaturally; the container visibly bends or twists in a way a rigid container couldn't; or the background changes or objects blink in and out.
level_2: Smaller but noticeable glitches: the shaking starts or stops instantly instead of easing in and out; the container's position drifts slightly (less than about 10% of the frame height) without any camera movement to explain it; there's a brief flicker or lighting mismatch lasting a couple of frames; or the image looks slightly warped near the edges only while the container is moving.
level_3: The container stays in the same place and orientation the whole time; the shaking motion is continuous and moves in one consistent pattern (no reversing or freezing partway through); the lighting stays steady with no sudden brightness or contrast changes; nothing appears or disappears out of nowhere; and the background stays the same and coherent throughout.
level_4: Everything in score 3 is present, and in addition the shaking has a natural back-and-forth rhythm (like a smooth swing that gradually settles, not a stiff robotic motion); the container's perspective stays consistent (no mismatched vanishing points or odd parallax); there's no jittering between frames; and any reflections or highlights on the container's surface move in a way that matches the shaking motion.
level_5: Everything in score 4 is present, and in addition the container's shaking motion stays within a single plane of movement (no unexpected wobble or roll out of that plane); the lighting and any shadows stay spatially coherent across every frame (nothing suggests the light source silently moved); reflections on the container's surface track the motion smoothly and correctly the whole time; and the moving container and liquid surface stay clear and readable throughout the shaking, without odd blur that would hide their edges.