Option 1: A wet towel dries in the sun.

This is a physical change because the water in the towel is simply evaporating when exposed to sunlight, changing its state from liquid to gas. The composition of the towel and water remains the same.

Option 3: Hot air rises over a radiator.

This is also a physical change. The movement of hot air over a radiator is a result of convection, where heated air expands and becomes less dense, causing it to rise. The air molecules themselves do not undergo any chemical reactions or changes.

Option 4: Coffee is brewed by passing steam through ground coffee.

This is a chemical change. Brewing coffee involves the process of extraction, where the steam interacts with the coffee grounds, extracting the flavors, oils, and compounds from the coffee. This chemical reaction results in the change of the composition and properties of the coffee.

Option 2: Lemon juice added to tea causing its color to change.

This is the correct answer. Mixing lemon juice with tea causes a chemical reaction to occur. The citric acid in the lemon juice reacts with the compounds present in the tea, leading to a change in color. The acidity of the lemon juice alters the pigments in the tea, resulting in a noticeable change in