Domain: Natural Science — Chemistry
Target concept: Sacrificial Anode Cathodic Protection

Video generation prompt: A beaker contains a sodium chloride solution simulating seawater. A zinc block is connected to a steel component, and both are immersed in the sodium chloride solution. A camera is directed at the beaker, and changes in the zinc block and steel component over time are observed using time-lapse photography.

Evaluation guide:
(i) Target concept: Electrochemical corrosion protection via galvanic coupling where a more active metal (Zn) corrodes to protect a less active metal (Fe in steel).
Minimum mechanism: A closed electrical circuit must exist (Zn–wire–steel–electrolyte–Zn); electrolyte must be conductive (NaCl solution); Zn must be thermodynamically more anodic than Fe (confirmed by standard electrode potentials); observable protection requires sufficient time for ion migration and surface product formation, captured here as progressive zinc surface change without concurrent steel degradation.
(ii)Storyline: Frame 1–2: Static shot showing beaker with NaCl solution, zinc block and steel component fully immersed and electrically connected. Frame 3–6: Zinc surface begins to lose metallic shine, becoming progressively duller and acquiring a heterogeneous gray-white deposit; steel remains uniformly reflective and unaltered. Frame 7–10: Zinc deposit coverage increases visibly (e.g., spreading from edges toward center); steel surface shows zero deviation from initial state: no texture shift, no color change, no flaking. Perspective: Fixed frontal view, centered on beaker interior; no occlusion; lighting from upper-front quadrant casting consistent soft shadows; all causal transitions (zinc change → steel stability) must be visually co-occurring and unambiguous within the 10-second sequence.

Manual:
Experimental Procedure
1. Fill a transparent cylindrical beaker with clear sodium chloride solution (simulating seawater).
2. Immerse a zinc block and a steel component side-by-side in the solution.
3. Electrically connect the zinc block to the steel component using a visible conductive wire or direct metallic clamp.
4. Position camera to capture full interior of beaker, ensuring both objects and their connection are continuously visible.
Observation of Experimental Phenomena
- Zinc block gradually dulls and develops a gray-white surface film or residue.
- Steel component retains its original metallic luster and shows no reddish-brown rust or pitting throughout.
Summary of Experimental Principles
- Zinc acts as a sacrificial anode: it oxidizes preferentially (Zn → Zn²⁺ + 2e⁻), supplying electrons to reduce oxygen/water at the steel cathode, thereby preventing iron oxidation (rust).

Prompt Grounding rubric:
level_1: No beaker present; or no sodium chloride solution visible in container; or zinc block absent; or steel component absent; or no electrical connection between zinc and steel; or camera view does not show interior of beaker with both objects immersed.
level_2: Beaker present with liquid, and either zinc block OR steel component is present and immersed, but the other is missing, disconnected, or not submerged; OR electrical connection exists but one object is outside solution; OR camera view shows only part of setup (e.g., only zinc or only steel, not both simultaneously in frame).
level_3: Beaker present containing visible liquid; zinc block and steel component both present, fully immersed in liquid; electrical connection (e.g., wire or direct metallic contact) visibly links zinc to steel; camera view shows entire beaker interior with both objects side-by-side in same scene, fixed viewpoint, no occlusion.
level_4: All conditions for score 3 satisfied AND zinc block is visibly distinct from steel component by color (dull gray matte vs. brighter metallic silver/gray) AND both objects maintain consistent spatial positions relative to each other and beaker throughout video (no teleportation, repositioning, or insertion mid-sequence).
level_5: All conditions for score 4 satisfied AND electrical connection is continuous and unbroken (no cut, gap, or disconnection visible at any frame) AND zinc block and steel component remain fully immersed without partial emergence or displacement AND liquid surface remains stable (no splashing, overflow, or artificial agitation) AND no extraneous objects (e.g., fingers, tools, labels) enter frame at any time.

Scientific and Causal Correctness rubric:
level_1: Zinc block shows no visible change while steel component corrodes (reddish-brown rust appears), OR steel corrodes while zinc remains unchanged in appearance, OR both corrode identically, OR zinc dissolves visibly (e.g., pitting, mass loss, bubbling) while steel remains pristine, all contradicting sacrificial anode principle.
level_2: Zinc block changes appearance (e.g., surface darkens, dulls, or develops white residue) but steel component also shows corrosion (reddish-brown discoloration or flaking); OR zinc shows no change while steel shows no change, implying no electrochemical activity; OR temporal order is reversed (steel changes before zinc shows any sign of reaction).
level_3: Zinc block exhibits visible surface change (e.g., dulling, graying, or formation of white/grey precipitate) AND steel component shows no reddish-brown corrosion or structural degradation at any frame, consistent with protection; AND change in zinc begins before or concurrently with observation window (no delay implying inactive system).
level_4: All conditions for score 3 satisfied AND zinc surface change is progressive (e.g., intensifies or spreads across surface over frames) AND steel remains uniformly metallic-gray with no localized discoloration, texture change, or flaking AND no gas bubbles appear at steel surface (which would indicate hydrogen evolution due to failed protection).
level_5: All conditions for score 4 satisfied AND zinc surface change is exclusively confined to zinc (no residue migrates onto steel) AND steel surface retains sharp, clean metallic luster and uniform reflectivity throughout AND no color shift (e.g., yellowing, bluing, or iridescence) appears on steel, confirming absence of oxidation or passivation failure.

Spatiotemporal Consistency rubric:
level_1: Objects appear/disappear abruptly between frames; zinc or steel teleports to new location; beaker or liquid flickers or vanishes; lighting changes discontinuously (e.g., full shadow to full highlight in one frame); liquid surface jumps or fractures unnaturally.
level_2: One or more objects exhibit unnatural motion (e.g., floating upward without buoyancy cue, rotating without pivot, vibrating erratically); electrical connection snaps or reconnects without physical cause; liquid surface ripples with no source or decays instantly; shadow direction flips inconsistently.
level_3: All objects maintain fixed spatial relationships: zinc and steel remain adjacent and stationary relative to beaker walls and each other; liquid surface stays level and continuous; lighting and shadow remain consistent in direction and intensity; no object fragments, merges, or deforms physically.
level_4: All conditions for score 3 satisfied AND motion (if any, e.g., subtle meniscus shift or settling) is smooth and continuous across frames (no stutter, jump-cut, or frame duplication); no inter-frame occlusion mismatch (e.g., finger appearing behind beaker then in front without parallax); no perspective warp (e.g., beaker shape distorting unnaturally).
level_5: All conditions for score 4 satisfied AND camera viewpoint remains absolutely fixed (no pan, tilt, zoom, or drift); no lens artifacts (e.g., chromatic aberration, vignetting, focus breathing); no temporal aliasing (e.g., strobing, rolling shutter skew on edges); liquid meniscus and object edges remain crisp and stable without shimmer or jitter.