Class 10 Chemical Reactions and Equations Important Questions

Important Questions Notes Previous Years Questions

Chemical Reactions and Equations Important Questions

1. What is a balanced chemical equation? Why is it important to balance a chemical equation?
2. Define exothermic reaction. Why respiration is considered as exothermic reaction?
3. A solution of substance ‘X’ is used for whitewashing.
   i. Name the substance ‘X’ & write its formula.
   ii. Write the reaction of ’X’ with water.
4. Write the balanced chemical equation when
   i. Hydrogen sulphide gas burns in air to give water & sulphur dioxide.
   ii. Barium chloride reacts with aluminium sulphate to give aluminium chloride & a precipitate of barium sulphate.
5. In electrolysis of water, why is the volume of gas collected over one electrode double that of the other electrode?
6. (a) Classify the following reactions into different types:
   (i) AgNO₃(aq) + NaCl(aq) →AgCl(s) + NaNO₃(aq)
   (ii) CaO(s) + H₂O(l)→Ca(OH)₂(aq)
   (iii) 2KClO₃ (s)→Δ2KCl(aq)+3O₂(g)
   (iv) Zn + CuSO₄ → ZnSO₄ + Cu
   (b) Translate the following statement into a balanced chemical equation:
   “Barium chloride reacts with aluminium sulphate to give aluminium chloride and barium sulphate.”
7. When potassium iodide solution is added to a solution of lead (II) nitrate in a test tube, a precipitate is formed.
   (a) What is the color of this precipitate? Name the compound precipitated.
   (b) Write the balanced chemical equation for this reaction.
   (c) List two types of reactions in which this reaction can be placed.
8. A substance X, which is an oxide of a group 2 element, is used intensively in the cement industry. This element is present in bones also. On treatment with water it forms a solution which turns red litmus blue. Identify X and also write the chemical reactions involved.
9. Why does the color of copper sulphate solution change when an iron nail is dipped in it? Write two observations.