Extra 40 multiple-choice questions (MCQs) with answers on Chapter:1 Chemical Reactions and Equations for Class 10 CBSE Science:

1-10: Basics of Chemical Reactions

A chemical reaction involves:
a) Breaking and making of chemical bonds
b) Only breaking of chemical bonds
c) Only making of chemical bonds
d) No change in chemical bonds
Ans: a) Breaking and making of chemical bonds

 

Which of the following is a physical change?
a) Rusting of iron
b) Melting of ice
c) Burning of wood
d) Digestion of food
Ans: b) Melting of ice

 

A chemical equation is balanced to satisfy:
a) Law of Conservation of Energy
b) Law of Conservation of Mass
c) Law of Gravity
d) Law of Motion
Ans: b) Law of Conservation of Mass

 

The reaction: 2Mg + O₂ → 2MgO is an example of:
a) Combination reaction
b) Decomposition reaction
c) Displacement reaction
d) Double displacement reaction
Ans: a) Combination reaction

 

What happens when magnesium ribbon burns in air?
a) A yellow flame is observed
b) A white powder is formed
c) A black residue is left
d) No reaction occurs
Ans: b) A white powder is formed

 

Which gas is released when zinc reacts with dilute hydrochloric acid?
a) Oxygen
b) Nitrogen
c) Hydrogen
d) Carbon dioxide
Ans: c) Hydrogen

 

The reaction 2H₂O₂ → 2H₂O + O₂ is an example of:
a) Combination reaction
b) Decomposition reaction
c) Displacement reaction
d) Double displacement reaction
Ans: b) Decomposition reaction

 

Which of the following metals does not react with dilute acids?
a) Zinc
b) Copper
c) Iron
d) Magnesium
Ans: b) Copper

 

In which type of reaction do two compounds exchange their ions?
a) Combination reaction
b) Decomposition reaction
c) Displacement reaction
d) Double displacement reaction
Ans: d) Double displacement reaction

 

Which of the following is an example of an exothermic reaction?
a) Dissolution of ammonium chloride
b) Electrolysis of water
c) Burning of coal
d) Melting of ice
Ans: c) Burning of coal

11-20: Types of Reactions

The reaction Zn + CuSO₄ → ZnSO₄ + Cu is an example of:
a) Combination reaction
b) Decomposition reaction
c) Displacement reaction
d) Double displacement reaction
Ans: c) Displacement reaction

 

The reaction CaCO₃ → CaO + CO₂ represents:
a) Combination reaction
b) Decomposition reaction
c) Displacement reaction
d) Redox reaction
Ans: b) Decomposition reaction

 

The reaction in which heat is absorbed is called:
a) Exothermic reaction
b) Endothermic reaction
c) Oxidation reaction
d) Reduction reaction
Ans: b) Endothermic reaction

 

Which metal does not react with water?
a) Sodium
b) Potassium
c) Gold
d) Magnesium
Ans: c) Gold

Rusting of iron occurs due to the presence of:
a) Air and water
b) Nitrogen and water
c) Carbon dioxide and water
d) Oxygen and nitrogen
Ans: a) Air and water

 

When silver chloride is exposed to sunlight, it turns:
a) White
b) Black
c) Blue
d) Red
Ans: b) Black

 

Which of the following is a redox reaction?
a) NaCl + AgNO₃ → AgCl + NaNO₃
b) 2H₂O → 2H₂ + O₂
c) Zn + HCl → ZnCl₂ + H₂
d) Both (b) and (c)
Ans: d) Both (b) and (c)

 

A reaction in which oxidation and reduction occur simultaneously is called:
a) Displacement reaction
b) Redox reaction
c) Combination reaction
d) Neutralization reaction
Ans: b) Redox reaction

 

Which of the following is an example of an oxidation reaction?
a) Burning of magnesium
b) Rusting of iron
c) Both (a) and (b)
d) None of the above
Ans: c) Both (a) and (b)

 

A substance that speeds up a chemical reaction without being consumed is called:
a) Catalyst
b) Reactant
c) Product
d) None of the above
Ans: a) Catalyst

 

The chemical formula of lime water is:
a) CaCO₃
b) Ca(OH)₂
c) CaCl₂
d) CaO
Ans: b) Ca(OH)₂

 

The chemical name of baking soda is:
a) Sodium hydroxide
b) Sodium carbonate
c) Sodium bicarbonate
d) Sodium chloride
Ans: c) Sodium bicarbonate

 

Photosynthesis is an example of:
a) Exothermic reaction
b) Endothermic reaction
c) Displacement reaction
d) Redox reaction
Ans: b) Endothermic reaction

 

The gas released when marble reacts with hydrochloric acid is:
a) Hydrogen
b) Oxygen
c) Carbon dioxide
d) Nitrogen
Ans: c) Carbon dioxide

 

A chemical reaction in which a compound breaks down into simpler substances is:
a) Combination reaction
b) Decomposition reaction
c) Displacement reaction
d) Redox reaction
Ans: b) Decomposition reaction

 

The reaction between an acid and a base is called:
a) Displacement reaction
b) Neutralization reaction
c) Redox reaction
d) Decomposition reaction
Ans: b) Neutralization reaction

The colour of copper sulphate solution is:
a) Green
b) Yellow
c) Blue
d) Red
Ans: c) Blue

 

What happens when ferrous sulphate is heated?
a) It turns blue
b) It decomposes into iron oxide, sulphur dioxide, and sulphur trioxide
c) It forms a new salt
d) No reaction occurs
Ans: b) It decomposes into iron oxide, sulphur dioxide, and sulphur trioxide

 

What is the chemical formula of quicklime?
a) CaCO₃
b) Ca(OH)₂
c) CaO
d) CaCl₂
Ans: c) CaO

 

The reaction between carbon dioxide and lime water forms:
a) Calcium chloride
b) Calcium hydroxide
c) Calcium carbonate
d) Calcium nitrate
Ans: c) Calcium carbonate

The process of depositing a layer of zinc on iron is called:
a) Galvanization
b) Rusting
c) Alloying
d) Corrosion
Ans: a) Galvanization

 

The element that undergoes oxidation is called:
a) Oxidizing agent
b) Reducing agent
c) Catalyst
d) Inhibitor
Ans: b) Reducing agent

 

The colour of silver chloride turns black due to:
a) Reaction with oxygen
b) Decomposition by light
c) Reaction with water
d) Heating
Ans: b) Decomposition by light

 

What type of reaction occurs in a glow stick?
a) Exothermic reaction
b) Chemiluminescence reaction
c) Redox reaction
d) Displacement reaction
Ans: b) Chemiluminescence reaction

 

Which reaction is used in black and white photography?
a) Neutralization reaction
b) Photochemical decomposition reaction
c) Combination reaction
d) Displacement reaction
Ans: b) Photochemical decomposition reaction

 

What is the pH of a neutral solution?
a) 7
b) 5
c) 9
d) 0
Ans: a) 7

 

What is the main component of rust?
a) Iron sulphate
b) Hydrated iron oxide
c) Ferrous chloride
d) Iron carbonate
Ans: b) Hydrated iron oxide

 

Electrolysis of water produces:
a) Hydrogen and carbon dioxide
b) Oxygen and carbon dioxide
c) Hydrogen and oxygen
d) Nitrogen and oxygen
Ans: c) Hydrogen and oxygen

 

What gas is evolved when sodium bicarbonate reacts with vinegar?
a) Oxygen
b) Hydrogen
c) Carbon dioxide
d) Nitrogen
Ans: c) Carbon dioxide

 

The burning of coal produces which gas?
a) Oxygen
b) Carbon dioxide
c) Hydrogen
d) Nitrogen
Ans: b) Carbon dioxide