Everything in this topic starts with one question: has a new substance actually formed?
In a physical change, the matter itself doesn't change into something new — it just looks or behaves differently. Melt ice into water, and you still have H₂O, just in a different state. Dissolve sugar in tea, and the sugar is still sugar, just spread out among the water molecules. Cut a sheet of paper into strips, and it's still paper.
The giveaway: physical changes are usually reversible. Freeze the water back into ice. Evaporate the tea and the sugar crystals are still there. Physical changes don't create anything new.
In a chemical change, the atoms in the starting materials rearrange into something with completely different properties — a new substance. Burn paper, and you get ash, carbon dioxide and water vapour — none of which is paper, and none of which turns back into paper on its own.
Chemical changes are usually hard or impossible to reverse by simple physical means (like cooling, cutting, or evaporating). You can't un-bake a cake or un-rust a nail.
Ice melting: still water (H₂O) before and after. Refreeze it and you're back where you started. Physical change.
Paper burning: paper (cellulose) turns into ash, CO₂ and water vapour — genuinely different substances, and you cannot turn the ash back into paper. Chemical change.
For each one, decide: does it just change form, or does it become something new?
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Nice work — that's the core skill for this whole topic.