A free original English–Hindi lesson on chemical change, equations and evidence. Distinguish physical change from new-substance formation; balance supplied valid equations by changing coefficients while preserving formulae. Track mass in stated open or closed accounts and consider reaction structure, overall heat transfer and suitable oxygen-transfer redox examples as separate questions. Eight worked cases, original representations, an analogy, a quick reference and ten questions with full explanations develop these distinctions. A balanced equation alone does not prove feasibility, speed or reactivity. The electron-accounting bridge is optional and excluded from compulsory review. All reaction cases are supplied descriptions for reasoning, not laboratory or chemical-handling instructions. This is focused topic practice, not a full science course or CBT simulation.