Domain: Natural Science — Atmospheric Science
Target concept: Photolysis of nitrogen dioxide (NO₂) in a sealed glass tube under ultraviolet irradiation

Video generation prompt: A sealed glass tube containing nitrogen dioxide (NO₂) is placed on the laboratory bench and exposed to ultraviolet light.

Evaluation guide:
(i) Target concept: Photolytic dissociation of nitrogen dioxide driven by ultraviolet photons resulting in loss of visible color due to elimination of the NO₂ chromophore.
Minimum mechanism: NO₂ must be present as a homogeneous, gaseous phase in a sealed, transparent container; UV photons must be absorbed by NO₂ molecules (λ < 400 nm); dissociation products (NO and O) must remain gaseous and colorless under conditions; no secondary reactions (e.g., NO oxidation) occur within observation time.
(ii)Storyline: [Phase 1: Baseline] Sealed glass tube with uniformly reddish-brown NO₂ gas rests motionless on bench; UV source is off or not yet illuminating. [Phase 2: Trigger] UV light engages and its beam makes stable contact with tube surface; no delay between illumination onset and observable effect initiation. [Phase 3: Transition] Reddish-brown color progressively and uniformly lightens along entire gas column; no spatial lag, streaking, or front propagation. [Phase 4: Endpoint] Gas reaches near-colorless state while remaining homogeneous and gaseous; tube remains sealed and structurally intact; UV remains incident. [Perspective/Visibility Constraints] Fixed frontal or slightly angled view showing full tube length; no occlusion; sufficient contrast to distinguish gas color against background; lighting avoids glare that masks color change.

Manual:
Experimental Procedure
1. Place a sealed glass tube containing nitrogen dioxide (NO₂) gas on a laboratory bench.
2. Shine ultraviolet light directly onto the tube.
Observation of Experimental Phenomena
The initially reddish-brown NO₂ gas gradually fades to pale yellow and finally becomes nearly colorless.
Summary of Experimental Principles
UV light provides energy to break the N=O bond in NO₂, producing colorless nitric oxide (NO) and atomic oxygen (O): NO₂ + hν (UV) → NO + O.

Prompt Grounding rubric:
level_1: No sealed glass tube is visible; no reddish-brown gas is present inside it; no ultraviolet light source is shown; there's no laboratory bench in the scene; the objects never appear placed together in one shot.
level_2: At least one of a glass tube, a bench, or a light source appears, but not correctly configured: e.g., the tube is open or empty, the gas's color is missing or wrong (colorless, blue, yellow), or the light isn't visibly aimed at the tube.
level_3: A sealed glass tube sits on a lab bench; it holds a visibly colored gas; a UV light is present and pointed toward the tube; the tube, gas, and light source all appear together in the same fixed shot, but the gas's color looks off, the seal isn't clearly visible, or the UV light isn't aimed right at the tube.
level_4: The sealed glass tube, the reddish-brown gas inside it, and the UV light source aimed at the tube are all present and correctly placed together; their spatial relationship stays the same throughout the clip; no object appears or disappears abruptly, and the tube and bench keep their shape and position with no sudden distortions.
level_5: All of 4 is met, AND the tube is clearly identifiable as sealed (e.g., fused ends or a stopper forming a visible seal); AND the UV light source looks distinct from ordinary room lighting (e.g., a visible purplish glow or a directional beam aimed at the tube); AND the bench has a smooth, non-wood surface finish typical of a lab bench; AND every object keeps the same size, position, and orientation across the whole clip.

Scientific and Causal Correctness rubric:
level_1: The gas's color never changes throughout the clip: it stays reddish-brown, white, or otherwise unchanged; or it disappears, condenses, or turns an impossible color like green or metallic; nothing links the UV exposure to any change in the gas.
level_2: The gas's color changes, but not the way NO₂ photolysis actually works: e.g., it gets darker brown instead of lighter, or jumps straight to fully clear with no fading step in between, or the color starts changing before the UV light is even on, or the gas seems to turn into visible particles, droplets, or a solid residue.
level_3: The reddish-brown gas inside the sealed tube visibly fades or lightens while the UV light is on; the fading only goes one direction and doesn't get darker again partway through; by the end it's noticeably paler or nearly clear, though the starting color may not read clearly as reddish-brown, or the timing of the fade relative to the UV switching on isn't obvious.
level_4: The gas starts out clearly reddish-brown; once the UV light hits it, the color steadily and continuously lightens with no reversal, no blotchy patches, and no localized bleaching; it ends up uniformly pale or nearly colorless; the fading only begins once the UV is fully on the tube; nothing extraneous like bubbling, condensation, or a pressure bulge appears.
level_5: All of 4 is met, AND the color moves through a believable sequence: reddish-brown to lighter brown to pale yellow to nearly colorless, matching how NO₂ breaking down into NO and O would look; nothing like glare, bloom, or motion blur obscures the change; the fading looks even across the whole gas column rather than streaked or stratified, consistent with a well-mixed gas.

Spatiotemporal Consistency rubric:
level_1: The sealed tube jumps to a different spot or disappears and reappears between frames; the gas's color vanishes or reappears with no fading in between; the bench surface flickers or warps; the UV light switches on and off instantly with visible frame jumps; shadows shift erratically across objects that aren't moving.
level_2: The tube wobbles or rotates as if unsupported; the gas appears to pulse or ripple in density for no reason; the bench's texture or perspective looks inconsistent frame to frame; the UV beam's direction shifts partway through without the light source itself moving; light and shadow edges jump or strobe.
level_3: The tube sits in the same spot the whole time with no jitter beyond what a static camera would show; the UV illumination stays steady in intensity; the gas's color looks uniform throughout its volume from one frame to the next, without patchy inconsistency; there are no structural breaks, and the tube, bench, and UV source keep the same spatial relationship to each other throughout.
level_4: All of 3 is met, AND the tube, bench, and UV source show no visible shift or distortion in position or orientation; the gas's color fades smoothly across frames without strobing or visibly skipping ahead in time; the shadows on the bench stay consistent with the UV source's position, with no brightness or contrast jump that isn't tied to the UV switching on.
level_5: All of 4 is met, AND any subtle motion (like the camera settling or faint air shimmer) looks physically plausible for a still lab bench; the gas's color fades smoothly with no abrupt jumps or blotchy patches in opacity; there's no ghosting or motion blur that obscures the color change; highlights and reflections on the glass tube stay stable and consistent with how glass reflects ambient light.