Domain: Natural Science — Chemistry
Target concept: White smoke formed by concentrated hydrochloric acid and concentrated ammonia solution

Video generation prompt: Hold two glass rods separately in concentrated hydrochloric acid and concentrated ammonia solution, respectively, then slowly bring them close together without any reagent dripping.

Evaluation guide:
(i) Target concept: Gas-phase diffusion and acid-base neutralization forming solid ammonium chloride aerosol.
Minimum mechanism: HCl(g) and NH₃(g) must be released from respective solutions, diffuse through air, meet in stoichiometric ratio near rod tips, and nucleate into submicron NH₄Cl crystals that scatter light as white smoke.
(ii)Storyline: Frame 0–2: Two stationary glass rods, each inserted vertically into distinct labeled containers (HCl left, NH₃ right), side-by-side in fixed frontal view; Frame 3–6: Rods move smoothly and linearly toward each other along parallel vertical axes, maintaining alignment and no tilt; Frame 7: Rod tips enter visual adjacency (gap < rod diameter); Frame 8: White smoke appears *exclusively* in inter-tip gap, expanding symmetrically; Frame 9–10: Smoke persists while rods hold position, then begins fading as rods separate—no residual smoke adhering to rods or containers. Visibility constraint: Entire process must be observable in single fixed viewpoint; no cutaways, zooms, or POV shifts.

Manual:
Experimental Procedure
1. Hold one glass rod vertically in a container of concentrated hydrochloric acid.
2. Hold another glass rod vertically in a separate container of concentrated ammonia solution.
3. Slowly bring the two rods closer together—tips approaching but never touching—until white smoke forms between them.
Observation of Experimental Phenomena
A dense, white, translucent smoke appears *only* in the narrow space between the approaching rod tips; no smoke forms before proximity, upon contact, or on rod surfaces.
Summary of Experimental Principles
Concentrated HCl releases HCl gas; concentrated NH₃ releases NH₃ gas; gases diffuse and react to form solid NH₄Cl particles, appearing as white smoke.

Prompt Grounding rubric:
level_1: No glass rods appear; there are no containers identifiable as concentrated hydrochloric acid or concentrated ammonia solution; and there is no action of holding rods or bringing them together.
level_2: Two glass rods appear, but at least one is not shown held in a container that can be identified, by label, liquid appearance, or context, as concentrated hydrochloric acid or concentrated ammonia solution; or the rods are never brought toward each other; or the two containers look identical or indistinguishable from one another.
level_3: Each glass rod is held in its own separate, visually distinguishable container -- one associated with concentrated hydrochloric acid, the other with concentrated ammonia solution; the two rods are brought toward each other within the same shot; and no liquid is shown dripping from either rod during the approach.
level_4: In addition to everything described for level 3: both containers keep a consistent, identifiable appearance (labeling, color, or context) throughout; the rods stay upright without tilting in a way that would cause dripping; and the rods keep closing the gap between them continuously until the smoke appears.
level_5: In addition to everything described for level 4: the two containers are shown side by side before the rods start moving; each rod is already inserted in its container when it first appears on screen; the rods move directly toward each other with no sideways or rotating drift; and neither liquid surface shows any splash or disturbance that would suggest a drip.

Scientific and Causal Correctness rubric:
level_1: No white smoke ever appears; or smoke appears while the rods are still far apart; or the smoke is colored (gray, blue, yellow) or looks like a thick, opaque fog rather than a light haze; or smoke is already present before the rods are brought near each other.
level_2: White smoke does appear, but only once the rods actually touch or overlap rather than while they are still close but separate; or smoke appears at the same moment as a visible drip or liquid transfer between the rods; or smoke starts forming while the rods are still clearly far apart, several rod-lengths from each other, which is inconsistent with a reaction that should only happen once the gases can meet and mix.
level_3: White smoke appears only once the two rods are close together and nearly touching but not touching; the smoke is white and translucent and stays localized in the gap between the tips; there is no color shift, trailing condensation, or leftover residue clinging to the rods once they separate.
level_4: Everything required at level 3 holds, and additionally: the sequence of events is clearly ordered -- no smoke, then the rods approach, then smoke appears between the tips, then the smoke thins out once the rods pull apart; and the smoke does not cling to the rod surfaces or drift upward in a way that looks unaffected by gravity or air movement.
level_5: Everything required at level 4 holds, and additionally: the smoke forms as a distinct, contained cloud centered in the gap between the tips; it spreads outward but stays centered between the rods rather than drifting to one side; its whiteness and translucency stay even, without streaking or sudden clumping; and it clears away noticeably soon after the rods stop approaching each other.

Spatiotemporal Consistency rubric:
level_1: A rod suddenly jumps to a new position; a container disappears or reappears; the lighting abruptly changes, such as a flash or blackout; a rod appears to break or snap mid-motion; or a shadow abruptly appears or vanishes with no visible cause.
level_2: The rods' motion looks noticeably choppy or stuttering rather than smooth; a hand or the edge of a container blocks a rod from view for a stretch that is clearly long enough to notice; a highlight or shadow on a rod's surface moves in a direction that does not match the apparent light source; or a container shifts position with no hand or other force visibly moving it.
level_3: Both rods keep a consistent spatial relationship to the camera as they move smoothly along paths that bring them together; the containers stay in place; the hands stay within the frame; the overall brightness and light direction stay steady, with no object flickering or shimmering at its edges.
level_4: All the level-3 criteria remain true, and additionally, the rods' motion looks continuous with no sudden speeding up, stopping, or restarting; the rod tips keep a steady orientation with no wobble or spinning; the background stays still and in focus; and the container and rod edges line up consistently from one frame to the next.
level_5: All the level-4 criteria remain true, and additionally, the sense of depth stays physically consistent -- the rods appear to grow subtly larger as they approach the camera-facing plane while background elements stay sharp and motionless; and the ordering of what is in front of what, such as a rod passing in front of a container, never contradicts itself across the sequence.