CBSE Class 10 Science Chemical Reactions and Equations MCQs Set D

Question: How many water molecules are present in a crystal of copper sulphate molecule?
a) 5
b) 7
c) 2
d) 3
Answer: a

Question: CuO + H₂ → H₂O + Cu, reaction is an example of –
a) redox reaction
b) synthesis reaction
c) neutralisation
d) analysis reaction
Answer: a

Question: Which of the following chemical equations is an unbalanced one ? 
a) 2NaHCO₃ → Na2CO₃ + H₂O + CO₂
b) 2C₄H1₀ + 12O₂ → + 8CO₂ + 10H₂O
c) 2Al + 6H₂O →2Al(OH)₃ + 3H₂
d) 4NH₃ + 5O₂ → 4NO + 6H₂O
Answer: b

Question: Which of the following gases can be used for storage
a) Carbon dioxide or Oxygen
b) Nitrogen or Oxygen
c) Carbon dioxide or Helium
d) Helium or Nitrogen
Answer: d

Question: Which of the following can be decomposed by the action of light?
a) NaCl
b) KCl
c) AgCl
d) CuCl
 Answer: c

Question: Which among the following is not a physical change?
a) Melting of solid to liquid.
b) Vaporisation of liquids to gas.
c) Liquefaction of gases to liquid.
d) Decay of matter.
Answer: d

Question: How many water molecules are present in a crystal of ferrous sulphate molecule?
a) 5
b) 2
c) 7
d) 10
Answer: c

Question: Which of the following is not a physical change?
a) Boiling of water to give water vapour.
b) Melting of ice to give water.
c) Dissolution of salt in water.
d) Combustion of Liquefied Petroleum Gas (LPG). 
Answer: d

Question:Which of the following is a thermal decomposition reaction?
a) 2H₂O → 2H₂+ O₂
b) 2AgCl → 2Ag + Cl₂
c) H₂(g) + Cl₂(g) → 2HCl(g)
d) ZnCO₃→ ZnO + CO₂
Answer: d

Question: Reaction between calcium oxide and water is a ______________ reaction.
a) endothermic reaction
b) decomposition reaction
c) exothermic reaction
d) displacement reaction
Answer: c

Question: Which of the following stands for a double displacement reaction ? 
a) 2H₂ + O₂ → 2H₂O
b) 2Mg + O₂ →2MgO
c) AgNO₃ + NaCl → AgCl + NaNO₃
d) H2 + Cl₂ → 2HCl
Answer: c

Question: The schematic diagram is given below

Which of the following is a correct statement ?

a) A and E are chemically same.
b) A and D are chemically same.
c) D and E are chemically same.
d) C and E are chemically same.
Answer: b

Question: The reaction, H₂ + Cl₂ →2HCl is
a) an oxidation reaction
b) a reduction reaction
c) a combination reaction
d) an isomerisation reaction
Answer: c

Question: Decomposition of water is
a) electrolytic
b) thermal
c) photolytic
d) All of the above
Answer: a

Question: When the gases sulphur dioxide and hydrogen sulphide mix in the presence of water, the reaction is SO₂ + 2H₂S → 2H₂O + 2S. Here hydrogen sulphide is acting as –
a) an oxidising agent
b) a reducing agent
c) a dehydrating agent
d) a catalyst
Answer: b

Question:When green coloured ferrous sulphate crystals are heated, the colour of the crystal changes because:
a) it is decomposed to ferric oxide
b) it loses water of crystallisation
c) it forms SO₂
d) it forms SO₃
Answer: b

Question: On the basis of following features, identify the correct option.
(i) This reaction occurs during corrosion.
(ii) This reaction occurs during respiration.
a) Decomposition reaction
b) Redox reaction
c) Combination reaction
d) Endothermic reaction
Answer: b

Question: Which of the following is a displacement reaction ? 
a) CaCO3 → CaO + CO₂
b) CaO + 2HCl →CaCl₂ + H₂O
c) Fe + CuSO4 → FeSO4 + Cu
d) NaOH + HCl →NaCl + H₂O
Answer: c

Question: Which of the following is a displacement reaction?

Answer: b

Question:The condition produced by aerial oxidation of fats and oils in foods marked by unpleasant smell and taste is called:
a) Antioxidation
b) Reduction
c) Rancidity
d) Corrosion
Answer: c

Question: Chemical changes are __________.
a) temporary, reversible and a new substance is produced.
b) always accompanied by exchange of light.
c) permanent, irreversible and a new substance is produced.
d) never accompanied by exchange of light and heat energy.
Answer: c

Question: Lead nitrate on heating gives
a) Lead oxide
b) Nitrogen dioxide
c) Oxygen
d) All of these
Answer: d

Question: Which of the following equations is representing combination of two compounds ? 
a) CaO + CO₂¾→ CaCO₃
b) CO +1/2O2 ¾→ CO₂
c) SO₂ +1/2O2 ¾→ SO₃
d) 2Na + 2H₂O ¾→ 2NaOH + H₂
Answer: a

Question: Fe2O₃ + 2Al ⎯⎯→ Al2O₃ + 2Fe
The above reaction is an example of a:
a) combination reaction
b) double displacement reaction
c) decomposition reaction
d) displacement reaction
Answer: d

Question: What is the colour of FeSO₄.7H₂O?
a) Blue
b) Green
c) White
d) Brown
Answer: b

Question: When hydrogen sulphide gas is passed through a blue solution of copper sulphate, a black precipitate of copper sulphide is obtained and the sulphuric acid so formed remains in the solution. The reaction is an example of –
a) a combination reaction
b) a displacement reaction
c) a decomposition reaction
d) a double decomposition reaction
Answer: d

Question: Which of the following is not a decomposition reaction ?
a) CaCO₃ → CaO + CO₂
b) 2KClO₃ →2KCl + 3O₂
c) Digestion of food in body
d) H₂ + Cl₂ →2HCl
Answer: d

Question: In which of the following the identity of initial substance remains unchanged?
a) Curdling of milk
b) Formation of crystals by process of crystallisation
c) Fermentation of grapes
d) Digestion of food
Answer: b

Question: Which of these will cause a chemical change to occur ?
a) Grinding of wheat into flour.
b) Lighting of a gas stove.
c) Evaporation of water from a lake.
d) Ringing of an electric bell.
Answer: b

Question: A balanced chemical equation is in accordance with –
a) Avogadro’s law
b) law of multiple proportion
c) law of conservation of mass
d) law of gaseous volumes.
Answer: c

Question: Physical changes are usually _______ in nature.
a) temporary
b) permanent
c) irreversible
d) endothermic
Answer: a

Question: What happens when copper rod is dipped in iron sulphate solution?
a) Copper displaces iron
b) Blue colour of copper sulphate solution is obtained
c) No reaction takes place
d) Reaction is exothermic
Answer: c

Question: Which of the following is a decomposition reaction?
a) ₂HgO ^Heat→2Hg + O₂
b) CaCO_3 ^Heat→CaO + CO₂
c) 2H₂O ^Electrolysi →H₂ + O₂
d) All of these
Answer: d

Question: Pb + CuCl₂ → PbCl₂ + Cu The above reaction is an example of:
a) combination
b) double displacement
c) decomposition
d) displacement 
Answer: d

Question:. Magnesium ribbon is rubbed before burning because it has a coating of
a) basic magnesium carbonate
b) basic magnesium oxide
c) basic magnesium sulphide
d) basic magnesium chloride
Answer: b

Question:PbS reacts with ozone (O₃) and forms pbso4 . As per the balanced equation, molecules of ozone required for every one molecule of PbS is/are
a) 4
b) 3
c) 2
d) 1
Answer: a

Question: Which of the following is an endothermic reaction?
a) CaCO₃ heat CaO + CO₂
b) CaO + H₂O Ca(OH)₂
c) C₆H₁₂O₆ + O2 6CO₂ + 6H₂O
d) None of these
Answer: a

Question: In the double displacement reaction between aqueous potassium iodide and aqueous lead nitrate, a yellow precipitate of lead iodide is formed. While performing the activity if lead nitrate is not available, which of the following can be used in place of lead nitrate?
a) Lead sulphate (insoluble)
b) (&) Lead acetate
c) Ammonium nitrate
d) Potassium sulphate 
Answer: b

Question: Select the oxidising agent for the following reaction:
H₂S + I₂ > 2HI + S
a) I₂
b) H₂S
c) HI
d) S
Answer: a

Question: In the equation Cu + xHNO₃ → Cu(NO₃)₂ + yNO₂ + 2H₂O The values of x and y are
a) 3 and 5
b) 8 and 6
c) 4 and 2
d) 7 and 1
Answer: c

Question: Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is:
a) 1 : 1
b) 2:1
c) 4:1
d) 1:2 
Answer: b

Assertion-Reason Questions

In the following question, a statement of Assertion
a) is followed by a statement of Reason (R). Answer these questions by selecting appropriate option given below:
a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A)
c) Assertion (A) is true but Reason (R) is false.
d) Assertion (A) is false but Reason (R) is true.

Question: Assertion (A): Pungent smelling gas is produced when sulphur burns in air.
Reason (R): Sulphur trioxide is formed on reaction of sulphur with oxygen.
Answer: c

Question: Assertion (A): To dilute sulphuric acid, acid is added to water and not water to acid.
Reason (R): Specific heat of water is quite large.
Answer: a

Question: Assertion (A): Calcium Carbonate when heated gives calcium oxide and water.
Reason (R): On heating CaCO₃, decomposition reaction takes place.
Answer: d

Question: Assertion (A): Sodium metal is stored under Kerosene.
Reason (R): Metallic sodium melts when exposed to air.
Answer: c

Question: Assertion (A): A reducing agent is a substance which can either accept electron.
Reason (R): A substance which helps in oxidation is known as reducing agent.
Answer: d

Question: Assertion (A): Quicklime reacts vigorously with water releasing a large amount of heat.
Reason (R): The above chemical reaction is an exothermic reaction.
Answer: a

Question: Assertion (A): Photosynthesis is considered as an endothermic reaction.
Reason (R): Energy gets released in the process of photosynthesis
Answer: c

Question: Assertion (A): Fe₂O₃ + 2Al → Al₂O₃ + 2Fe The above chemical equation is an example of displacement reaction.
Reason (R): Aluminium being more reactive than iron, displaces Fe from its oxide.
Answer: a

Question: Assertion (A): Stannous chloride is a powerful oxidising agent which oxidises mercuric chloride to mercury.
Reason (R): Stannous chloride gives grey precipitate with mercuric chloride, but stannic chloride does not do so.
Answer: c

Question: Assertion (A): Carbon dioxide turns lime water milky.
Reason (R): Carbon dioxide sullies the water.
Answer: c

Very Short Answer Type Questions

Question: What happens when quicklime is added to water?
Answer: Quicklime reacts with water vigorously to produce slaked lime and a large amount of heat.

Question: State one basic difference between a physical change and a chemical change.
Answer: In a physical change, no new substance is formed. In a chemical change, a new substance is formed.

Question: Which one is a chemical change-rusting of iron or melting of iron?
Answer: Rusting of iron.

Question: What happens when ZnCO₃ is heated in the absence of air? Give the relevant equation.
Answer: ZnO(s) and CO₂(g)CO₂(g) are formed. Chemical Equation:
ZnCO₃ → ZnO + CO₂

Question: Name and state the law which is kept in mind while we balance a chemical equation.
Answer: Law of conservation of mass. Mass can neither be created nor be destroyed during a chemical reaction.