"on heating iron ore with carbon we got iron and carbon dioxide" is this synthesis, decomposition, or replacement

It should be a single replacement if the iron ore was an iron oxide (FeO), since the iron in the oxide was replaced by carbon, making CO and leaving iron (Fe) alone.

Answeroutward from: source;

The chemical reactions lab we did is typically called a "copper plating lab,  because the acid solution cleaned the pennies and made the copper look shinier;   the acid solution cleaned the paperclips and made them look like pennies;   &   the copper from the pennies was removed, and then added to the paperclips.