Determine which one of these everyday substances is a pure substance.IronDirty dishwaterMilkConcrete

To determine which one of these everyday substances is a pure substance, we need to understand what a pure substance is. A pure substance consists of only one type of element or compound and has a uniform composition throughout.

1. Iron: Iron is a chemical element with the symbol Fe. It is a pure substance because it consists of only one type of atom.

2. Dirty dishwater: Dirty dishwater is a mixture of water, soap, food particles, and other contaminants. It is not a pure substance because it contains multiple components.

3. Milk: Milk is a mixture of water, fats, proteins, lactose, and various other substances. It is not a pure substance because it contains multiple components.

4. Concrete: Concrete is a mixture of cement, water, sand, and gravel. It is not a pure substance because it contains multiple components.

Therefore, the pure substance among the given options is Iron.