ZnCO₃ → ZnO + CO₂. Zinc oxide is yellow when hot, white when cold (reversible). The gas carbon dioxide turns limewater milky; acid on a carbonate gives effervescence.
A solid in a liquid is separated by filtration: solid = residue on the paper, liquid = filtrate below.
Your written answers are checked offline against the mark scheme's required points using keyword and synonym patterns (e.g. "ppt" = "precipitate", "milky" = limewater positive). Each point you make earns its marks; the feedback tells you what's still missing so you can re-mark.