ABK –SSJ Class X
Ch-1 CHEMICAL REACTIONS & EQUATIONS
CLASS X SCIENCE PREVIOUS YEAR QUESTIONS
_______________________________________________________________________________________
ABK -SSJ
Join our Telegram channel for notes and lectures: https://t.me/ABKSSJ2021
Download our app : https://hodor.page.link/vEwC
Characteristics of a Chemical reaction
1.With the help of an appropriate example, justify that some of the chemical reactions are determined by(CBSE
2023)
(a) Change in temperature,
(b) Evolution of a gas,
(c) Change in colour and
Give chemical equation for the reaction involved in each case.
Ans. (a) CaO + H2O → Ca (OH)2 + Heat
(b) Zn + H2SO4 → ZnSO4 + H2(g)
(c) CuSO4.5H2O → CuSO4 + 5H2O
(Blue) (White)
2.State the change in colour observed in each of the following cases mentioning the reason(CBSE 2023)
(a)Silver chloride is exposed to sunlight.
(b)A piece of zinc is dipped in ferrous sulphate solution
(c)Copper powder is strongly heated in air.
Ans.(i)Photo decomposition of silver chloride takes place which results in the formation of silver and colour changes
to grey.
(ii) Copper undergoes oxidation and black coloured copper oxide is formed.
(iii) Zinc displaces copper and the solution changes from blue to colourless due to the formation of zinc sulphate.
Identify the Type & Balanced Chemical Equations
3.(a) What is meant by balanced chemical equation? Why chemical equations are balanced ?
(b) Balance the chemical equation given below
Al2O3+NaOH →NaAlO2+H2O
Ans.(a) A chemical equation in which the number of atoms of each element remains the same, before and after a
chemical reaction.
•Chemical equations are balanced to satisfy the law of conservation of mass.
(b) Al2O3 + 2NaOH → 2NaAlO2 + H2O
4.Identify the type of reaction from the following equations:
(i) CH4 +2O2 → CO2 + 2H2O
(ii) Pb(NO3)2 + 2KI → Pbl₂+ 2KNO3
(iii) CaO+ H₂O → Ca(OH)2
(iv) CuSO4 + Zn → ZnSO4 + Cu
Subscribe our youtube channel ABK-SSJ : https://www.youtube.com/@ABKSSJ
,Ans.(i)Combustion or redox reaction
(ii)Double displacement or precipitation reaction
(iii)Combination reaction
(iv)Displacement reaction
5.Write down the balanced chemical equations for the following reactions and identify the type of reaction in each
case. (CBSE 2023)
(a) Nitrogen gas is treated with hydrogen gas to form ammonia gas.
(b) Lead nitrate is heated strongly to form lead monoxide, nitrogen dioxide and oxygen.
(c) A copper wire is dipped in silver nitrate solution to form copper nitate solution and a shining deposit of silver is
produced.
Ans.(a) Combination reaction; N2 + 3H2 → 2NH3
(b) Decomposition reaction / Thermal Decomposition ;2Pb(NO3)2 Heat 2PbO + 4NO2 + O2
(c) Displacement reaction; Cu + 2AgNO3 →Cu(NO3)2 + 2Ag
6.Classify the following reactions into different types:(CBSE 2019)
(i) AgNO3 (aq) + NaCl (aq) →AgCl (s) + NaNO3 (aq)
(ii) CaO (s) + H2O (𝑙) → Ca(OH)2 (aq)
(iii) 2KCIO3 (s) → 2KCI (aq) + 3O2 (g)
(iv) Zn + CuSO4 → ZnSO4 + Cu
(b) Translate the following statement into a balanced chemical equation : ‘‘Barium chloride reacts with aluminium
sulphate to give aluminium chloride and barium sulphate.’’
Ans.(a) (i) double displacement reaction
(ii) combination reaction
(iii) decomposition reaction
(iv) displacement reaction
(b) 3BaCl2 + Al2(SO4)3 → 2AlCl3 + 3BaSO4
7.State the kind of chemical reactions in the following examples
(i) Digestion of food in stomach
(ii) Combustion of coal in air
(iii) Heating of limestone
Ans.(i) Decomposition reaction or Exothermic reaction
(ii)Combination reaction
(iii) Decomposition reaction
8.Identify the type of reactions taking place in each of the following cases and write the balanced chemical equation
for the reactions.
(a) Zinc reacts with silver nitrate to produce zinc nitrate and silver.
(b) Potassium iodide reacts with lead nitrate to produce potassium nitrate and lead iodide.
Ans.(a) Displacement reaction
Zn + 2 AgNO3 → Zn (NO3)2 + 2 Ag
(b) Double displacement reaction
2 KI + Pb (NO3)2 → PbI2 + 2KNO3
Subscribe our youtube channel ABK-SSJ : https://www.youtube.com/@ABKSSJ
,Combination & Exothermic Reaction
9.A shining metal ‘M’, on burning gives a dazzling white flame and changes to a white powder ‘N’.
(a) Identify ‘M’ and ‘N’.
(b) Represent the above reaction in the form of a balanced chemical equation.
(c) Does ‘M’ undergo oxidation or reduction in this reaction ? Justify
Ans.(a) ‘M’ is magnesium /Mg ‘N’ is Magnesium oxide / MgO
(b) 2Mg + O2 → 2MgO
(c) ‘M’ undergoes oxidation because oxygen is added to it.
10.Solid calcium oxide was taken in a container and water was added slowly to it.
(i) State two observations made in the experiment.
(ii) Write the balanced chemical equation of this reaction
Ans. Exothermic reaction : Reaction in which heat is released.
(b) CaO+ H2O Ca (OH)2
(c ) (i) Calcium oxide reacts vigorously with water.
(ii) Large amount of heat is released.
11.A compound ‘A’ is used in the manufacture of cement. When dissolved in water, it evolves a large amount of heat
and forms compound ‘B’.
(i) Identify A and B.
(ii) Write chemical equation for the reaction of A with water.
(iii) List two types of reaction in which this reaction may be classified.
Ans.(i) A = CaO / Quick lime/ Calcium oxide
B = Ca(OH)2 / Slaked lime / Calcium hydroxide
(ii) CaO + H2O → Ca(OH)2
(iii) Combination reaction or Exothermic reaction
12.A small amount of quick lime is added to water in a beaker.
(i) Name and define the type of reaction that has taken place.
(ii) Write balanced chemical equation for the above reaction and the chemical name of the product formed.
(iii) List two main observations of this reaction.
Ans.(i) Combination reaction: A combination reaction is a reaction where two or more elements or compounds
combine to form a single compound.
(ii) CaO + H2O → Ca(OH)2 + Heat Energy
Quick lime Calcium Hydroxide
Chemical name of the product formed lime)
(iii) Observations of the reactions:
• Reaction takes place vigorously
• Large amount of heat is released.
Decomposition & Endothermic Reaction
13.In the electrolysis of water
(a) Name the gases liberated at anode and cathode.
(b) Why is it that the volume of gas collected on one electrode is two times that on the other electrode ?
Subscribe our youtube channel ABK-SSJ : https://www.youtube.com/@ABKSSJ
, (c) What would happen if dil. H2SO4 is not added to water ?
Ans.(a) Anode- Oxygen Cathode- Hydrogen
(b) Because one molecule of water contains two atoms of hydrogen and one atom of oxygen
2H2O → 2H2+O2
(c) Electrolysis of water will not take place
14.Study the figure given below and answer the following questions :
(a) Name the process depicted in the diagram.
(b) Write the composition of the anode and the cathode.
(c) Write the balanced chemical equation of the reaction taking place in this case.
(d) The reaction does not take place if a few drops of dilute sulphuric acid are not added to water. Why ?
Ans.(a) Electrolysis of water.
(b) Carbon electrodes / Graphite rod
(c) 2H2O Electric Current 2H2 + O2
(d) Pure water is a non conductor of electricity /electric current is carried through the acidic solution by ions
(i) While electrolysing water before passing the current some drops of an acid are added. Why ?
15.Name the gases liberated at cathode and anode. Write the relationship between the volume of gas collected at
anode and the volume of gas collected at cathode.
(ii) What is observed when silver chloride is exposed to sunlight ? Give the type of reaction involved.
Ans.(i) • To increase the conductivity of water
• Hydrogen – cathode Oxygen – anode
• Anode : Cathode
1:2
Volume of hydrogen liberated at cathode is twice that of oxygen liberated at anode.
(ii) • White silver chloride turns grey
• Decomposition reaction / Photolytic Decomposition
16.2 g of ferrous sulphate crystals are heated in a dry boiling tube. (CBSE 2019)
(a) List any two observations.
(b) Name the type of chemical reaction taking place.
(c) Write balanced chemical equation for the reaction and name the products formed.
Ans. (a) Observations :
i. Colour changes from green to white.
ii. Formation of reddish brown Ferric oxide (Fe2O3) / evolution of SO2 / SO3 gas.
(b) Decomposition reaction
Subscribe our youtube channel ABK-SSJ : https://www.youtube.com/@ABKSSJ
Ch-1 CHEMICAL REACTIONS & EQUATIONS
CLASS X SCIENCE PREVIOUS YEAR QUESTIONS
_______________________________________________________________________________________
ABK -SSJ
Join our Telegram channel for notes and lectures: https://t.me/ABKSSJ2021
Download our app : https://hodor.page.link/vEwC
Characteristics of a Chemical reaction
1.With the help of an appropriate example, justify that some of the chemical reactions are determined by(CBSE
2023)
(a) Change in temperature,
(b) Evolution of a gas,
(c) Change in colour and
Give chemical equation for the reaction involved in each case.
Ans. (a) CaO + H2O → Ca (OH)2 + Heat
(b) Zn + H2SO4 → ZnSO4 + H2(g)
(c) CuSO4.5H2O → CuSO4 + 5H2O
(Blue) (White)
2.State the change in colour observed in each of the following cases mentioning the reason(CBSE 2023)
(a)Silver chloride is exposed to sunlight.
(b)A piece of zinc is dipped in ferrous sulphate solution
(c)Copper powder is strongly heated in air.
Ans.(i)Photo decomposition of silver chloride takes place which results in the formation of silver and colour changes
to grey.
(ii) Copper undergoes oxidation and black coloured copper oxide is formed.
(iii) Zinc displaces copper and the solution changes from blue to colourless due to the formation of zinc sulphate.
Identify the Type & Balanced Chemical Equations
3.(a) What is meant by balanced chemical equation? Why chemical equations are balanced ?
(b) Balance the chemical equation given below
Al2O3+NaOH →NaAlO2+H2O
Ans.(a) A chemical equation in which the number of atoms of each element remains the same, before and after a
chemical reaction.
•Chemical equations are balanced to satisfy the law of conservation of mass.
(b) Al2O3 + 2NaOH → 2NaAlO2 + H2O
4.Identify the type of reaction from the following equations:
(i) CH4 +2O2 → CO2 + 2H2O
(ii) Pb(NO3)2 + 2KI → Pbl₂+ 2KNO3
(iii) CaO+ H₂O → Ca(OH)2
(iv) CuSO4 + Zn → ZnSO4 + Cu
Subscribe our youtube channel ABK-SSJ : https://www.youtube.com/@ABKSSJ
,Ans.(i)Combustion or redox reaction
(ii)Double displacement or precipitation reaction
(iii)Combination reaction
(iv)Displacement reaction
5.Write down the balanced chemical equations for the following reactions and identify the type of reaction in each
case. (CBSE 2023)
(a) Nitrogen gas is treated with hydrogen gas to form ammonia gas.
(b) Lead nitrate is heated strongly to form lead monoxide, nitrogen dioxide and oxygen.
(c) A copper wire is dipped in silver nitrate solution to form copper nitate solution and a shining deposit of silver is
produced.
Ans.(a) Combination reaction; N2 + 3H2 → 2NH3
(b) Decomposition reaction / Thermal Decomposition ;2Pb(NO3)2 Heat 2PbO + 4NO2 + O2
(c) Displacement reaction; Cu + 2AgNO3 →Cu(NO3)2 + 2Ag
6.Classify the following reactions into different types:(CBSE 2019)
(i) AgNO3 (aq) + NaCl (aq) →AgCl (s) + NaNO3 (aq)
(ii) CaO (s) + H2O (𝑙) → Ca(OH)2 (aq)
(iii) 2KCIO3 (s) → 2KCI (aq) + 3O2 (g)
(iv) Zn + CuSO4 → ZnSO4 + Cu
(b) Translate the following statement into a balanced chemical equation : ‘‘Barium chloride reacts with aluminium
sulphate to give aluminium chloride and barium sulphate.’’
Ans.(a) (i) double displacement reaction
(ii) combination reaction
(iii) decomposition reaction
(iv) displacement reaction
(b) 3BaCl2 + Al2(SO4)3 → 2AlCl3 + 3BaSO4
7.State the kind of chemical reactions in the following examples
(i) Digestion of food in stomach
(ii) Combustion of coal in air
(iii) Heating of limestone
Ans.(i) Decomposition reaction or Exothermic reaction
(ii)Combination reaction
(iii) Decomposition reaction
8.Identify the type of reactions taking place in each of the following cases and write the balanced chemical equation
for the reactions.
(a) Zinc reacts with silver nitrate to produce zinc nitrate and silver.
(b) Potassium iodide reacts with lead nitrate to produce potassium nitrate and lead iodide.
Ans.(a) Displacement reaction
Zn + 2 AgNO3 → Zn (NO3)2 + 2 Ag
(b) Double displacement reaction
2 KI + Pb (NO3)2 → PbI2 + 2KNO3
Subscribe our youtube channel ABK-SSJ : https://www.youtube.com/@ABKSSJ
,Combination & Exothermic Reaction
9.A shining metal ‘M’, on burning gives a dazzling white flame and changes to a white powder ‘N’.
(a) Identify ‘M’ and ‘N’.
(b) Represent the above reaction in the form of a balanced chemical equation.
(c) Does ‘M’ undergo oxidation or reduction in this reaction ? Justify
Ans.(a) ‘M’ is magnesium /Mg ‘N’ is Magnesium oxide / MgO
(b) 2Mg + O2 → 2MgO
(c) ‘M’ undergoes oxidation because oxygen is added to it.
10.Solid calcium oxide was taken in a container and water was added slowly to it.
(i) State two observations made in the experiment.
(ii) Write the balanced chemical equation of this reaction
Ans. Exothermic reaction : Reaction in which heat is released.
(b) CaO+ H2O Ca (OH)2
(c ) (i) Calcium oxide reacts vigorously with water.
(ii) Large amount of heat is released.
11.A compound ‘A’ is used in the manufacture of cement. When dissolved in water, it evolves a large amount of heat
and forms compound ‘B’.
(i) Identify A and B.
(ii) Write chemical equation for the reaction of A with water.
(iii) List two types of reaction in which this reaction may be classified.
Ans.(i) A = CaO / Quick lime/ Calcium oxide
B = Ca(OH)2 / Slaked lime / Calcium hydroxide
(ii) CaO + H2O → Ca(OH)2
(iii) Combination reaction or Exothermic reaction
12.A small amount of quick lime is added to water in a beaker.
(i) Name and define the type of reaction that has taken place.
(ii) Write balanced chemical equation for the above reaction and the chemical name of the product formed.
(iii) List two main observations of this reaction.
Ans.(i) Combination reaction: A combination reaction is a reaction where two or more elements or compounds
combine to form a single compound.
(ii) CaO + H2O → Ca(OH)2 + Heat Energy
Quick lime Calcium Hydroxide
Chemical name of the product formed lime)
(iii) Observations of the reactions:
• Reaction takes place vigorously
• Large amount of heat is released.
Decomposition & Endothermic Reaction
13.In the electrolysis of water
(a) Name the gases liberated at anode and cathode.
(b) Why is it that the volume of gas collected on one electrode is two times that on the other electrode ?
Subscribe our youtube channel ABK-SSJ : https://www.youtube.com/@ABKSSJ
, (c) What would happen if dil. H2SO4 is not added to water ?
Ans.(a) Anode- Oxygen Cathode- Hydrogen
(b) Because one molecule of water contains two atoms of hydrogen and one atom of oxygen
2H2O → 2H2+O2
(c) Electrolysis of water will not take place
14.Study the figure given below and answer the following questions :
(a) Name the process depicted in the diagram.
(b) Write the composition of the anode and the cathode.
(c) Write the balanced chemical equation of the reaction taking place in this case.
(d) The reaction does not take place if a few drops of dilute sulphuric acid are not added to water. Why ?
Ans.(a) Electrolysis of water.
(b) Carbon electrodes / Graphite rod
(c) 2H2O Electric Current 2H2 + O2
(d) Pure water is a non conductor of electricity /electric current is carried through the acidic solution by ions
(i) While electrolysing water before passing the current some drops of an acid are added. Why ?
15.Name the gases liberated at cathode and anode. Write the relationship between the volume of gas collected at
anode and the volume of gas collected at cathode.
(ii) What is observed when silver chloride is exposed to sunlight ? Give the type of reaction involved.
Ans.(i) • To increase the conductivity of water
• Hydrogen – cathode Oxygen – anode
• Anode : Cathode
1:2
Volume of hydrogen liberated at cathode is twice that of oxygen liberated at anode.
(ii) • White silver chloride turns grey
• Decomposition reaction / Photolytic Decomposition
16.2 g of ferrous sulphate crystals are heated in a dry boiling tube. (CBSE 2019)
(a) List any two observations.
(b) Name the type of chemical reaction taking place.
(c) Write balanced chemical equation for the reaction and name the products formed.
Ans. (a) Observations :
i. Colour changes from green to white.
ii. Formation of reddish brown Ferric oxide (Fe2O3) / evolution of SO2 / SO3 gas.
(b) Decomposition reaction
Subscribe our youtube channel ABK-SSJ : https://www.youtube.com/@ABKSSJ
