CBSE Class 10 Chemistry Chemical Reactions And Equation Worksheet Set E

Question. A dilute ferrous sulphate solution was gradu¬ally added to the beaker containing acidified permanganate solution. The light purple colour of the solution fades and finally disap¬pears. 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 de-composes in presence of FeSO₄. to a colourless compound

Answer: A

Question. When Zinc pieces are added to dilute HCl taken in a test tube, then:
(a) No change takes place
(b) The colour of the solution becomes yellow.
(c) A pungent smelling gas gets liberated
(d) Small bubbles of H₂ gas appear on the surface of zinc pieces

Answer: D

Question. Copper displaces which of the following metals from its salt solution:
(a) ZnSO₄
(b) FeSO₄
(c) AgNO₃
(d) NiSO₄

Answer: C

Question. Chemically rust is:
(a) Hydrated ferrous oxide
(b) Hydrated ferric oxide
(c) Only ferric oxide
(d) None of these

Answer: A,B

Question. Which of the following statements about the given reaction are correct?
3Fe (s) + 4H₂O (g) → Fe3O₄ (s) + 4 H₂ (g)
(i) Iron metal is getting oxidised
(ii) Water is getting reduced
(iii) Water is acting as reducing agent
(iv) Water is acting as oxidising agent
(a) (i), (ii) and (iii) (b) (ii) and (iv)
(c) (i), (ii) and (iv) (d) (ii) and (iv)

Answer: C

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. In the reaction:
PbO + C→ Pb + CO
(a) PbO is oxidised
(b) C acts as an oxidising agent
(c) Carbon acts as a reduction agent
(d) Reaction does not represent redox reaction.

Answer: C

Question. The reaction H₂ + Cl₂ → 2 HCl represents:
(a) oxidation
(b) reduction
(c) decomposition
(d) combination

Answer: D

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. We store silver chloride in dark colored bottles because it is
(a) A white solid
(b) Undergoes redox reaction
(c) To avoid action by sunlight
(d) None of the above.

Answer: C

ASSERTION- REASON QUESTIONS :

DIRECTION: Each of these questions contains an Assertion followed by Reason. Read them carefully and answer the question on the basis of following options. You have to select the one that best describes the two statements.
(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If Assertion is incorrect but Reason is correct

Question. Assertion: In a reaction.
Zn(s) + CuSO₄ (aq) → ZnSO4 (aq) + Cu(s) Zn is a reductant but itself get oxidized.
Reason: In a redox reaction, oxidant is reduced by accepting electrons and reductant is oxidized by losing electrons.

Answer: A

Question. Assertion: The balancing of chemical equations is based on law of conservation of mass.
Reason: Total mass of reactants is equal to total mass of products.

Answer: A

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

Answer: C

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

Answer: D

Question. Assertion: Corrosion of iron is commonly known as rusting.
Reason: Corrosion of iron occurs in presence of water and air.

Answer: B

CASE STUDY BASED QUESTIONS:

1. Read the following and answer the questions :
A student was asked to investigate what happens when a piece of shiny magnesium ribbon is added to copper sulphate solution. The apparatus was set up as shown below. The mass was recorded at the start and again after one hour. 

Question. Complete the equation:
Mg + CuSO₄ →--------- + ---------
(a) MgSO₄ + Cu
(c) MgS + Cu₂O
(b) MgO + Cu
(d) Mg SO₃ + Cu₂O

Answer: A

Question. Choose from below the name given to this type of reaction:
(a) Combustion
(b) Displacement
(c) Corrosion
(d) Electrolysis

Answer: B

Question. Balance the following symbol equation that represents the displacement reaction that takes place between zinc and silver nitrate solution.
Zn + AgNO₃ → Zn(NO₃)₂ + Ag
(a) Zn + 2AgNO₃ → Zn(NO₃)₂ + 2Ag
(b) Zn + 3AgNO₃ → Zn(NO₃)₂ + 3Ag
(c) Zn + 2AgNO₃ → Zn(NO₃)₂ + Ag
(d) 2 Zn + AgNO₃ → Zn(NO₃)₂ + Ag

Answer: A

Question. The experiment was repeated using sodium sulphate solution instead of copper sulphate solution.
No reaction took place. Put the metals copper, magnesium and sodium in order of reactivity.
(a) I. Sodium II Copper III Magnesium
(b) I Magnesium II Copper III Sodium
(c) I. Copper II. Magnesium III. Sodium
(d) I. Sodium II. Magnesium III. Copper

Answer: D

Question. What will be the mass of the beaker and content after 1 hour?
(a.) More than 80.6 g
(b) Equal to 80.6 g
(c) Less than 80.6 g
(d) None of the above

Answer: B

2. Read the following and answer the questions : 

Called the reducing agent; when the reaction occurs, it reduces the other species. In other words, what is oxidized is the reducing agent and what is reduced is the oxidizing agent.
A good example of a redox reaction is the thermite reaction, in which iron atoms in ferric oxide lose (or give up) O atoms to Al atoms, producing Al2O₃.
Fe₂O₃ (s) +2Al (s)→Al₂O₃ (s)+2Fe (l)

Question. Which of the following is correct code for X and Y in the following reaction? 

(i) x=oxidation reaction, y=reduction reaction
(ii) x=gain of two electrons, y=loss of two electrons,
(iii) x=reduction reaction, y=oxidation reaction
(iv) x=loss of two electrons, y=gain of two electrons
(a) (i) and (ii)
(b) (i) and (iv)
(c) (ii) and (iii)
(d) (iii) and (iv)

Answer: B

Question. A substance which oxidizes itself and reduces other is known as:
(a) Oxidizing agent
(b) Reducing agent
(c) Both of these
(d) None of these

Answer: B

Question. ‘Thermite is a pyrotechnic composition of metal powder, which serves as fuel, and metal oxide.
When ignited by heat, thermite undergoes a reaction between iron and Aluminum Oxide and is used in the wielding of railway tracks. The type of reaction is called:
(a) Reduction
(c) Redox
(b) Oxidation
(d) Decomposition

Answer: C

Question. “Redox reactions can occur relatively slowly, as in the formation of rust, or much more rapidly, as in the case of burning fuel” Rusting and combustion are quite different. Which of the following lines is not the correct explanation for this?
(a) Rusting occurs at the surface of iron to form a layer of rust.
(b) Rusting gives out lots of heat and light.
(c) Rusting is an example of slow oxidation.
(d) It can be hampered by applying paint.

Answer: B

Question. Reduction can be defined as:
(a) Gain of electrons
(b) Gain of Oxygen
(c) Loss of Hydrogen
(d) Loss of electrons

Answer: A

3. Read the following and answer the questions :
Oxidation is the process of gaining of oxygen, or losing of hydrogen. Reduction is the process of losing of oxygen or gaining of hydrogen. The substance which undergoes oxidation is the reducing agent while the substance which undergoes reduction is known as the oxidising agent. Oxidation and reduction always take place together and these types of reactions are known as redox reactions. Some of the examples of redox reactions are given below:

Question. Give two examples of oxidation reaction from your everyday life.
Answer: corrosion & rancidity

Question. Write the oxidising agent in the reaction III and VI.
Answer: CuSO₄ in (III) & CuO in(VI)

Question. Which of the following is an oxidising agent?
(a) LiAlH₄
(b) Alkaline KMnO4
(c) Acidified K₂Cr₂O₇
(d) Both (b) and (c)
Answer: D

Question. Out of oxidation and reduction, which reaction takes place at anode?
Answer: oxidation

Question. Which substance undergoes reduction?
Answer: oxidizing agent

4. Read the following and answer the questions :
A chemical reaction is a representation of chemical change in terms of symbols and formulae of reactants and products. There are various types of chemical reactions like combination, decomposition, displacement, double displacement, oxidation and reduction reactions. Reactions in which heat is released along with the formation of products are called exothermic chemical reactions. All combustion reactions are exothermic reactions.

Question. The chemical reaction in which a single substance breaks down into two or more simpler substances upon heating is known as
(a) thermal decomposition reaction
(b) photo decomposition reaction
(c) electric decomposition reaction
(d) both (a) and (c)

Answer: A

Question. The massive force that pushes the rocket forward through space is generated due to the
(a) combination reaction
(b) decomposition reaction
(c) displacement reaction
(d) double displacement reaction

Answer: B

Question. A white salt on heating decomposes to give brown fumes and yellow residue is left behind. The yellow residue left is of
(a) lead nitrate
(b) nitrogen oxide
(c) lead oxide
(d) oxygen gas

Answer: C

Question. Which of the following reactions represents a combination reaction?
(a) CaO (s) + H₂O (l) → Ca(OH)₂ (aq)
(b) CaCO₃ (s) → CaO (s) + CO₂(g)
(c) Zn(s) + CuSO₄ (aq) → ZnSO₄ (aq) + Cu(s)
(d) 2FeSO₄(s) → Fe2O₃ (s) +SO_2(g) + SO₃(g)

Answer: A

Question. Complete the following statements by choosing correct type of reaction for X and Y.
Statement 1: The heating of lead nitrate is an example of ‘X’ reaction.
Statement 2: The burning of magnesium is an example of ‘Y’ reaction.
(a) X- Combination, Y- Decomposition
(b) X- Decomposition, Y-Combination
(c) X- Combination, Y-Displacement
(d) X- Displacement, Y-Decomposition

Answer: B

5. Read the following and answer the questions :
Chemical equation is a method of representing a chemical reaction with the help of symbols and formulae of the substances involved in it. In a chemical equation, the substances which combine or react are called reactants and new substances produced are called products. A chemical equation is a short hand method of representing a chemical reaction. A balanced chemical equation has equal number of atoms of different elements in the reactants and products side. An unbalanced chemical equation has unequal number of atoms of one or more elements in reactants and products. Formulae of elements and compounds are not changed to balance an equation.

Question. Consider the following reaction:
pMg₃N₂ + qH₂O ⇾ rMg(OH)₂ + sNH₃
When the equation is balanced, the coefficients p, q, r, s respectively is
(a) 1,3,3,2
(c) 1,6,3,2
(b) 1,2,3,2
(d) 2,3,6, 2

Answer: B

Question. Which of the following information is not conveyed by a balanced chemical equation?
(a) Physical states of reactants and products
(b) Symbols and formulae of all the substances involved in a particular reaction
(c) Number of atoms/molecules of the reactants and products formed
(d) Whether a particular reaction is actually feasible or not

Answer: D

Question. The balancing of chemical equations is in accordance with
(a) Law of combining volumes
(b) Law of constant proportions
(c) Law of conservation of mass
(d) Both (b) and (c)

Answer: C

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 statements is/are correct?
(a) A chemical equation tells us about the substances involved in a reaction.
(b) A chemical equation informs us about the symbols and formulae of the substances involved in a reaction.
(c) A chemical equation tells us about the atoms or molecules of the reactants and products involved in a reaction.
(d) All the above.

Answer: D

 

1. What happens chemically when quicklime is added to water filled in a bucket?

 

2. Why do potato chips manufacturers fill the packet of chips with nitrogen gas?

 

3. Write a balanced chemical equation to represent decomposition of lead nitrate on heating. What are brown fumes due to? Mention one commercial use of this salt.

 

4. What change of colour is observed when white silver chloride is left exposed to sunlight? State the type of chemical reaction in this change.

 

5. Why is it necessary to balance a chemical equation?

 

6. Write the following in the form of balanced chemical equations: -

 

(a) Calcium carbonate decomposes on heating to form calcium oxide and carbon dioxide.

 

(b) When ammonium hydroxide is added to a solvent of iron (II) Sulphate, a green precipitate of iron (II)hydroxide and ammonium Sulphate are formed.

 

(c) When a nail of iron is added to a solution of copper Sulphate, iron (II) Sulphate and copper metal are formed.

 

(d) Zinc reacts with dil. hydrochloric acid to form zinc chloride and hydrogen gas is liberated.

 

7. Balance the following equations.

 

a) MnO₂+ HCI→MnCI₂+ H₂O+Cl₂

 

b) NH₃+ O₂→ NO+ H₂O

 

c) C₄H₁₀+O₂→CO₂+ H₂O

 

d) Fe₂(SO₄)₃ +BaCl₂→FeCl₃+BaSO₄

 

e) Cu + HNO₃→NO₂+H₂O+Cu(NO₃)₂

 

f) KClO₃ →KCl + O₂

 

g) Na + H₂O →NaOH + H₂

 

h) ZnS + O₂→ZnO + SO₂

 

i) MgCl₂ + NaOH → Mg(OH)₂ + NaCl

 

j) NH4Cl + Ca(OH)₂→CaCl₂+NH₃ +H₂O

 

k) Al₂O₃ + →NaAlO₂ + H₂O l) C₂H₅OH + O₂ → CO₂ + H₂O.

 

8. (a) A solution of substance “X “ is used for white washing. What is the substance” X” ? State the chemical reaction of X with water.

 

9. What is a decomposition reaction?. Give 2 examples each of decomposition taking place due to heat, light and electricity.

 

10. Identify the type of reactions:-

 

(a) 4Na + O₂ → 2Na₂O

 

(b) Cu + 2AgNO₃ →Cu (NO₃)₂ + 2Ag

 

(c) FeSO₄ → Fe₂O₃ + SO₂ + SO₃

 

(d) AgNO₃ + NaCl →AgCl +NaNO₃

 

(e) CaO + CO₂ →CaCO₃

 

11. Consider the following chemical reaction

 

X + Barium chloride → Y + Sodium chloride

 

(a) Identify X and Y.

 

(b) The type of reaction.

 

12. On heating blue coloured powder of copper (II) nitrate in boiling tube ,copper oxide (black),oxygen gas and a brown gas ‘X ’is formed. (a) Write a balanced chemical equation of the reaction.( b) Identify the brown gas‘X’evolved ( c) Identify the type of reaction

 

13. Find out the process of oxidation, reduction ,oxidizing agent, reducing agent from the following:-

 

(a) MnO₂ + 4HCl -→ MnCl₂ + 2H₂O + Cl₂

 

(b) CuO + C → Cu + CO

 

14. Name the compounds formed when Fe, Cu, Ag and Al get corroded.

 

15. What is rancidity? Explain two ways by which food industries prevent rancidity.

 

16 .What is Corrosion? Suggest any two ways to prevent rusting of Iron.

 

17.Write balanced chemical equation for the reactions that take place during respiration. Identify the type of combination reaction that takes place during this process and justify the name. Give one more example of this type of reaction.

 

18. 2g of ferrous sulphate crystals are heated in a dry boiling tube.

 

(a) List any two observations.

(b) Name the type of chemical reaction taking place.

(c) Write the chemical equation for the reaction.

 

19. Distinguish between a displacement reaction and a double displacement reaction .Give one example each.

 

20. Name the reducing agent in the following reaction:

 

3MnO₂ + 4 Al → 3 Mn + 2 Al₂O₃

 

State which is more reactive, Mn or Al and why?