They are pure substances. Each has an exact formula.
It is a compound: NaCl-sodium [an element] bonded to chloride [an element].
It is a mixture
Sodium chloride(NaCl),common salt.
Common salt is a compound, formed from the reaction between sodium and chlorine, giving NaCl, sodium chloride, common salt.
Sodium itself is an element, not a compound. If you are talking about dietary sodium, the most common source that to get that from is the compound sodium chloride (salt).
Aluminum is an element (pure metal), not a compound.
To determine the oxidation number of an element in a chemical compound, you need to follow these steps: Identify the element in the compound. Determine the common oxidation states for that element. Assign the oxidation number based on the compound's overall charge and known rules for assigning oxidation numbers. By following these steps, you can accurately determine the oxidation number of an element in a chemical compound.
Fluoride is an ion of the element fluorine. So it is not a compound. However sometimes the compound sodium fluoride, a common ingredient in toothpaste, is simply referred to a fluoride.
element. Sulfur dioxide (SO2) is a compound
Calcite is not an element. It is a mineral which is made up of the elements calcium, carbon, and oxygen.In chemistry it is known as the compound calcium carbonate, CaCO3
KCl is a compound not an element.
cornstarch is a compound element.