Q1.CorrosionEasy · 1m
What is corrosion?
Answer: The slow damage of a metal by the action of air, moisture or chemicals around it — for example the rusting of iron.
Class 10 · Science · Important Questions
Chemical Reactions and Equations — Important Questions
Q2.BalancingEasy · 2m
Why must a chemical equation be balanced?
Answer: Because of the law of conservation of mass — matter is neither created nor destroyed, so the number of atoms of each element must be equal on both sides.
Q3.DisplacementMedium · 2m
What happens when an iron nail is dipped in copper sulphate solution?
Answer: Iron, being more reactive, displaces copper: Fe + CuSO₄ → FeSO₄ + Cu. The blue colour fades and a brown copper coating forms on the nail.
Q4.RancidityMedium · 2m
What is rancidity and how can it be prevented?
Answer: Rancidity is the change in smell and taste of fats and oils due to oxidation. It can be slowed by adding antioxidants, packing food in nitrogen, or storing it in airtight containers in the cold.
Q5.TypesMedium · 3m
Define a decomposition reaction and give one example.
Answer: A reaction in which a single compound breaks down into two or more simpler substances, for example 2H₂O → 2H₂ + O₂ on electrolysis.
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