Mixture or pure substance: 1.water 2.blood 3.the oceans 4.iron 5.brass 6.uranium 7.wine 8.leather 9.table salt (nacl)

Any element or compound is a PURE SUBSTANCE.
1. Water is a PURE SUBSTANCE because it contains only Water molecules.
2. Blood contains a lot of things so it is a MIXTURE of salt, iron, nutrients, etc.
3. The oceans is obviously a MIXTURE because it has salt and water.
4. Iron is a PURE SUBSTANCE with a chemical element with symbol Fe.
5. Brass is a MIXTURE of copper and zinc.
6. Uranium is a PURE SUBSTANCE with a chemical element with symbol U.
7. Wine is a MIXTURE of water, sugar, alcohol.
8. Leather is a MIXTURE of skin and rubber, etc.
9. Table Salt (NaCl) is a PURE SUBSTANCE because it's a compound.
Hope that helps.

When you are making a guess you are forming a hypothesis