To determine which substance is most likely a mixture, let's analyze each substance based on the given descriptions:
1. Substance P: "Formed by boiling pure water"
- Boiling pure water simply changes its state from liquid to gas (steam). Since both liquid water and steam consist of the same molecule, [tex]\( \text{H}_2\text{O} \)[/tex], this substance remains a pure substance.
2. Substance Q: "Formed by combining three hydrogen atoms to every nitrogen atom"
- This description matches the chemical composition of ammonia, [tex]\( \text{NH}_3 \)[/tex]. Ammonia is a pure compound because it consists of molecules with a fixed ratio of hydrogen to nitrogen.
3. Substance R: "Formed by adding 5 g of sugar to 1 L of water"
- When sugar (a solid) is added to water (a liquid) and dissolves, it creates a solution. This solution is a mixture because it involves combining substances (sugar and water) without a fixed chemical composition.
4. Substance S: "Formed by compressing carbon under high pressure"
- Compressing carbon under high pressure can produce diamond. Diamond is a pure substance made entirely of carbon atoms arranged in a crystal lattice structure.
Considering these analyses:
- P is a pure substance.
- Q is a pure substance.
- R is a mixture (sugar solution).
- S is a pure substance.
Therefore, based on the descriptions, the substance most likely a mixture is:
[tex]$ \mathbf{R} $[/tex]
