To identify which situations contain chemical changes, let's analyze each option:
I) A pot of water is being heated on a stove. Bubbles form and condensation appears on the lid of the pot.
- This is a physical change (water boiling) as it involves a change in state from liquid to gas and back, but no new substances are formed.
II) A translucent, blue copper (II) sulfate solution is mixed with water and changes to a translucent lighter blue color.
- This is primarily a physical change; the concentration of the solution changes but no chemical reaction occurs, and the substance remains copper (II) sulfate in solution.
III) Ammonium nitrate solid is added to water and the temperature drops significantly.
- This represents a chemical change as the dissolution of ammonium nitrate absorbs heat from the surroundings, leading to an endothermic reaction, although it might not form new substances, it does involve a chemical process.
IV) Red and blue paint are mixed together and the color purple appears.
- This is a physical change, as mixing paints does not involve a chemical reaction; it's simply a combination of pigments.
Based on this analysis, the situations that involve chemical changes are:
- III only, but since it's a matter of context that often leads to confusion about whether or not mixing paints is considered a chemical change, it should be noted that if strictly speaking based on the question provided, none of the options explicitly state that III is solo which may be somewhat misleading.
If the answer options were to highlight the most definitive chemical change from the choices, then option D (III only) would be the closest correct response.