* Gold: Gold is an element, not a compound. It's found naturally in its pure form and is not a combination of multiple elements.
* Iodine: Iodine is also an element, not a compound.
* Sand: Sand is a mixture of different materials, primarily silica (silicon dioxide). It's not a compound in the chemical sense.
* Water: Water is a compound made up of two hydrogen atoms and one oxygen atom (H₂O).
So, the only example of a compound in your list is water.
Which is better?
That depends on your criteria:
* For a simple, common compound: Water is a great example.
* For a complex compound: There are many other complex compounds out there, like table salt (NaCl), sugar (C₁₂H₂₂O₁₁), or DNA.
* For something with interesting properties: Some compounds have unique properties, like gold chloride (AuCl₃) which is used in photography and electronics.
Ultimately, the "best" example depends on what you are looking for and why.
