Chemical Reactions and Equations – Class 10 Important Questions (Only Questions)

 

Chemical Reactions and Equations – Class 10 Important Questions (Only Questions)

Subject: Science (Chemistry)
Class: 10
Board: CBSE
Chapter No.: 1
Chapter Name: Chemical Reactions and Equations
Session: 2025–26

Q. No. 1) Multiple Choice Questions (MCQs)

i. Which of the following reaction(s) is an endothermic reaction?
ii. You are given the solution of lead nitrate. In order to obtain a yellow precipitate you should mix with it a solution of ______.
iii. Which of the following are exothermic processes?
iv. Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during the electrolysis of water is ______.
v. Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by the liberation of heat. This process is called slaking of lime. Which among the following is/are true about slaking of lime?
vi. Identify the endothermic reaction(s) among the following:
vii. Which of the following statements about the given reaction are correct?
3Fe + 4H2O → Fe3O4 + 4H2
viii. Sunita takes about 2 g ferrous sulphate crystals in a dry boiling tube and heats it. The color of crystals after heating is ______.
ix. The silver chloride is placed under the sunlight. The color of silver chloride after some time is ______.
x. A small amount of copper powder is heated. Which reaction shows the above reaction?
xi. The following reactions are carried out in open vessels. Which of the following correctly shows if the weight of the reaction vessel and contents increases, decreases, or remains the same?
xii. Identify the product which represents the solid state in the reaction given.

Q. No. 2) Assertion-Reason Questions

i. Assertion (A): A white-washed wall develops a coating of calcium carbonate after a few days.
Reason (R): Calcium oxide on the wall reacts slowly with carbon dioxide in the air.

ii. Assertion (A): Following is a balanced chemical equation for the action of steam on iron:
3Fe + 4H2O → Fe3O4 + 4H2
Reason (R): The law of conservation of mass holds good for a chemical equation.

iii. Assertion (A): While balancing a chemical equation, we alter the formula of the compounds involved.
Reason (R): A chemical equation is balanced by making the number of atoms of each element equal.

iv. Assertion (A): In the reaction
MnO2 + 4HCl → MnCl2 + 2H2O + Cl2
HCl is getting oxidized while MnO2 is getting reduced.
Reason (R): The process in which oxygen is added is called oxidation whereas removal of oxygen is called reduction.

Q. No. 3–19: Short & Long Answer Questions

  1. Why is magnesium ribbon cleaned with sandpaper before burning? What residue is obtained after burning? Write the balanced chemical equation.
  2. Dilute HCl is added to Zn granules. How will you prove that a chemical change has taken place?
  3. Define a chemical reaction. State four observations that help determine whether a chemical reaction has taken place, with examples.
  4. Which among the following are physical or chemical changes?
    (a) Evaporation of petrol (b) Burning of LPG (c) Heating of iron rod to red hot (d) Curdling of milk (e) Sublimation of ammonium chloride.
  5. (a) Define a balanced chemical equation. Why should an equation be balanced?
    (b) Write balanced equations for:
    i. Phosphorus burns in chlorine to form PCl5.
    ii. Burning of natural gas.
    iii. The process of respiration.
  6. Why does a clear solution of slaked lime turn milky on exposure to air? Explain with an equation.
  7. Identify the type of reaction in:
    (a) A + BC → AC + B
    (b) AB + CD → AC + BD. Give examples with balanced equations.
  8. Identify the type of chemical reaction in the following:
    (a) Digestion of food (b) Rusting of iron (c) Heating MnO2 with Al powder (d) Reaction of dilute HCl with NaOH.
  9. 2 g of ferrous sulphate crystals are heated in a boiling tube.
    (i) List two observations.
    (ii) Name the type of chemical reaction.
    (iii) Write the balanced chemical equation.
  10. On heating blue copper nitrate, copper oxide, oxygen, and a brown gas are formed.
    (a) Write balanced equation.
    (b) Identify the brown gas.
    (c) Identify the type of reaction.
    (d) State the pH range of the aqueous solution of the gas.
  11. Students electrolyze acidified water.
    (a) Name the gases collected at cathode and anode.
    (b) Why is one gas collected in double volume?
    (c) Write the balanced equation.
  12. Why is silver chloride stored in dark bottles? What happens when it is exposed to sunlight? Write the reaction and its application.
  13. Give one example each of decomposition reactions carried out with the help of:
    (i) Electricity (ii) Heat (iii) Light.
  14. When KI solution is added to Pb(NO3)2 solution, a precipitate forms.
    (i) What is the color and name of the compound?
    (ii) Write the balanced chemical equation.
    (iii) Name two types of reactions this belongs to.
  15. Write balanced chemical equations for reactions (a) to (o) as given in your syllabus (Na2CO3 with HCl, NaHCO3 with HCl, CuSO4 with KI, Pb(CH3COO)2 with HCl, Thermit reaction, etc.).
  16. Identify the oxidizing agent in the given reactions.
  17. Identify the reducing agent in the given reactions.


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