The item that is a salt from the list you provided is calcium carbonate.
Here's a quick breakdown of the others:
- Carbonate acid is not a specific term; you might be referring to carbonic acid, which is an acid and not a salt.
- Acid is a general term and does not refer to a specific substance.
- Sodium hydroxide is a strong base, not a salt.
Salts are typically formed from the neutralization reaction between an acid and a base, and calcium carbonate (CaCO₃) is indeed a salt derived from the reaction of carbonic acid (H₂CO₃) and calcium hydroxide (Ca(OH)₂).
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