CBSE Class 10 Science Chemical Reactions and Equations MCQs Set H

Question. Which among the following is not a physical change ?
(a) Evaporation of petrol
(b) Burning of liquified petroleum gas (LPG)
(c) Heating of an iron rod to red hot.
(d) Sublimation of solid ammonium chloride
Answer: b

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 liquified petroleum gas (LPG)
Answer: d

Question. Which of the following reactions is an endothermic reaction?
(a) Burning of coal.
(b) Decomposition of vegetable matter into compost.
(c) Process of respiration.
(d) Decomposition of calcium carbonate to form quick lime and carbon dioxide.
Answer: d

Question. In the given equation, what does ‘X’ stand for ?
(2)Al + (X)H₂SO₄ → Al₂(SO₄)₃ + (3)H₂
(a) 2
(b) 3
(c) 1
(d) 5
Answer: b

Question. There is an equation ‘X’, which contains equal number of atoms of each element on both the sides. What is ‘X’?
(a) A balanced equation
(b) An unbalanced equation
(c) A chemical equation
(d) All of the above
Answer: a

Question. In which of the following chemical equations, the abbreviations represent the correct states of the reactants and products involved at reaction temperature?
(a) 2H₂(l) + O₂(l) → 2H₂O(g)
(b) 2H₂(g) + O₂(l) → 2H₂O(l)
(c) 2H₂(g) + O₂(g) → 2H₂O(l)
(d) 2H₂(g) + O₂(g) → 2H₂O(g)
Answer: c

Question. The reaction in which a substance or substances undergo change to produce new substances with new properties is called
(a) A biochemical reaction
(b) A nuclear reaction
(c) A physical reaction
(d) A chemical reaction 
Answer: d

Question. Which of the following conditions is necessary for a chemical reaction?
(a) It must be accompanied with change in temperature and pressure.
(b) At least one of the reactants must be in a fixed quantity.
(c) It must follow the law of conservation of mass.
(d) All of the above.
Answer: c

Question. A dilute ferrous sulphate solution was gradually added to the beaker containing acidified permanganate solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation?
(a) KMnO₄ is an oxidising agent, it oxidises FeSO₄.
(b) FeSO₄ acts as an oxidising agent and oxidises KMnO₄.
(c) The colour disappears due to dilution; no reaction is involved.
(d) KMnO₄ is an unstable compound and decomposes in presence of FeSO₄ to a colourless compound.
Answer: a

Question. Which one of the following processes involve chemical reactions?
(a) Storing of oxygen gas under pressure in a gas cylinder
(b) Liquification of air
(c) Keeping petrol in a china dish in the open
(d) Heating copper wire in presence of air at high temperature 
Answer: d

Question. Three beakers labelled as A, B and C each containing 25 mL of water were taken. A small amount of NaOH, anhydrous CuSO₄ and NaCl were added to the beakers A, B and C respectively. It w as observed that there was an increase in the temperature of the solutions contained in beakers A and B, whereas in case of beaker C, the temperature of the solution falls. Which one of the following statement(s) is (are) correct?
(i) In beakers A and B, exothermic process has occurred.
(ii) In beakers A and B, endothermic process has occurred.
(iii) In beaker C, exothermic process has occurred.
(iv) In beaker C, endothermic process has occurred.
(a) (i) only
(b) (ii) only
(c) (i) and (iv)
(d) (ii) and (iii)
Answer: c

Question. Which among the following is (are) double displacement reaction(s)?
(i) Pb + CuCl₂ → PbCl₂ + Cu
(ii) Na2SO₄ + BaCl₂ → BaSO₄ + 2NaCl
(iii) C + O₂ → CO₂
(iv) CH₄ + 2O₂ → CO₂ + 2H₂O U
(a) (i) and (iv)
(b) (ii) only
(c) (i) and (ii)
(d) (iii) and (iv)
Answer: b

Question. The following reaction is an example of a 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g)
(i) Displacement reaction
(ii) Combination reaction
(iii) Redox reaction
(iv) Neutralisation reaction
(a) (i) and (iv)
(b) (ii) and (iii)
(c) (i) and (iii)
(d) (iii) and (iv)
Answer: b

Question. Barium chloride on reacting with ammonium sulphate forms barium sulphate and ammonium chloride. Which of the following correctly represents the type of the reaction involved?
(i) Displacement reaction
(ii) Precipitation reaction
(iii) Combination reaction
(iv) Double displacement reaction
(a) (i) only
(b) (ii) only
(c) (iv) only
(d) (ii) and (iv)
Answer: d

Assertion And Reason Based MCQs :

Directions : In the following questions, A statement of Assertion (a) is followed by a statement of Reason (R). Mark the correct choice as.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is NOT the correct explanation of A.
(c) A is true but R is false.
(d) A is false and R is true.

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

Question. Assertion (A): A chemical reaction becomes faster at higher temperatures. 
Reason (R): At higher temperatures, molecular motion becomes more rapid.
Answer: a

Question. Assertion (a): After white washing the walls, a shiny white finish on walls is obtained after two to three days.
Reason (R): Calcium oxide reacts with carbon dioxide to form calcium hydrogen carbonate which gives shiny white finish.
Answer: c

Question. Assertion (A): Burning of candle is a physical change.
Reason (R): In physical change, no new substance is formed.
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): 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: In the reaction : MnO2 + 4HCl → MnCl₂ + 2H₂O + Cl₂ HCl is getting oxidized while MnO₂ is getting reduced. 
Reason: The process in which oxygen is added to a substance is called oxidation.
Answer: a

Question. Assertion (A): Chips manufacturers usually flush bags of chips with gas such as nitrogen.
Reason (R): Nitrogen gas prevents the oil and fats of the chips from being oxidized.
Answer: a

Read the following and answer any four questions from Chemistry in Automobiles:

For an internal combustion engine to move a vehicle down the road, it must convert the energy stored in the fuel into mechanical energy to drive the wheels. In your car,the distributor and battery provide this starting energy by creating an electrical “spark”,which helps in combustion of fuels like gasoline. Below is the reaction depicting complete combustion of gasoline in full supply of air:
2C8H18(l) + 25O2(g) ¾® 16 ‘X’ + Y

Question. ‘A student while walking on the road observed that a cloud of black smoke belched out from the exhaust stack of moving trucks on the road.’ Choose the correct reason for the production of black smoke:
(a) Limited supply of air leads to incomplete combustion of fuel.
(b) Rich supply of air leads to complete combustion of fuel.
(c) Rich supply of air leads to a combination reaction.
(d) Limited supply of air leads to complete combustion of fuel.
Answer: a

Question. ‘Although nitrogen is the most abundant gas in the atmosphere, it does not combustion’. Identify the correct reason for this statement.
(a) Nitrogen is a reactive gas
(b) Nitrogen is an inert gas
(c) Nitrogen is an explosive gas
(d) Only hydrocarbons can take part in combustion
Answer: b

Question. Which of the following are the products obtained from the reaction mentioned in the above case? Product ‘X’ Product ‘Y’
(a) CO₂ H2O₂
(b) H₂O CO
(c) CH₃OH H₂O
(d) CO₂ H₂O
Answer: d

Question. Identify the types of chemical reaction occurring during the combustion of fuel:
(a) Oxidation & Endothermic reaction
(b) Decomposition & Exothermic reaction
(c) Oxidation & Exothermic reaction
(d) Combination & Endothermic reaction
Answer: c

Question. On the basis of evolution/absorption of energy, which of the following processes are similar to combustion of fuel?
(i) Photosynthesis in plants
(ii) Respiration in the human body
(iii) Decomposition of vegetable matter
(iv) Decomposition of ferrous sulphate.
(a) (ii) & (iii)
(b) (i) & (ii)
(c) (iii) & (iv)
(d) (ii) & (i)
Answer: a