Class 10th Sample paper
Chemical Reaction and Equations
Q1. What happens chemically when quick lime is added to water?
Q2. How will you test for the gas which is liberated when HCL reacts with an active metal?
Q3. What is an oxidation reaction? Is it exothermic or endothermic? Give one example of oxidation Reaction.
Q4. Give an example of photochemical reaction.
Q5. Give an example of a decomposition reaction. Describe any activity to illustrate such a reaction by heating.
Q6. Why is respiration considered as exothermic process?
Q7. Balance the following chemical equation.
Fe(s) +H2O(g) = Fe3O4 + H2(g)
MnO2 + HCL = MnCl2 + Cl2 + H2O
HNO3 + Ca(OH)2 = Ca(NO3)2 + H2O
Q8. On what basis is a chemical equation balanced?
Q9. State any two observations in an activity suggesting the occurrence of a chemical reaction.
Q10. Name a reducing agent which may be used to obtain manganese from manganese dioxide.
Q11. What change in colour is observed when silver chloride is left exposed to sunlight? Also mention the type of chemical reaction.
Q12. Define a combination reaction. Give one example of an exothermic combination reaction.
Q13. What is observed when a solution of potassium iodide is added to lead nitrate solution?
What type of reaction is this? Write a balanced chemical equation for this reaction.
Q14. Distinguish between an exothermic and an endothermic reaction.
Q15. Distinguish between a displacement and a double displacement reaction.
Q16. Identify the type of reaction in the following:
Fe + CuSO4(aq) = FeSO4(aq) + Cu(s)
2H2 + O2 = 2H2O
Answers
1. Quick Lime stands for CaO.
CaO + H2O ➵ Ca(OH)2
Ca(OH)2 is commanly called Lime water or Slaked lime that turns milky on passing CO2.
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2. Take any metal, for example Na(Sodium). Then,
Na + HCl ➵ NaCl + H2
In order to test this gas, bring a burning candle near the test tube which which will explode with a pop up sound.
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3. Oxidation reaction is a reaction in which products get oxidised to produce large amount of energy.
For example :-
C6H12O6 ➵ Pyruvate ➵ 6CO2 + 6H2O + 38ATP (Energy)
Hence it is an exothermic reaction.
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5. CaCO3 + Heat ➵ CaO + CO2
• Take a test tube and heat it on bunsen burner.
• You will found a powdary substance at bottom called CaO (Quick lime).
• Trap the gas evolved and pass it through Lime water. It turns milky therefore gas evolved is CO2.
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6. In respiration, molecules of Energy (ATP) are produced and whenever energy is produced as a product then reaction is termed as Exothermic.
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7. Balanced Equations
• 3Fe(s) +4H2O(g) ➵ Fe3O4 + 4H2(g)
• MnO2 + 4HCL ➵ MnCl2 + Cl2 + 2H2O
• 2HNO3 + Ca(OH)2 ➵ Ca(NO3)2 + 2H2O
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8. Chemical Equation is balanced on the basis of number of atoms present in reactants and products.
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9. • Evolution of gas
Evolution of gas• Change in colour.
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10. Reaction :
MnO2 + 2H2 ➵ Mn + 2H2O
Hence H2 is reducing agent for Mangenese Dioxide.
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11. Reaction :
AgCl + Light ➵ Ag + Cl2
AgCl was white (precipitate) while on getting exposed to light it breaks into Ag which is silver in colour.
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12. When simple substances combine to form single compound is called combination reaction.
Example :-
C + O2 ➵ CO2 + Energy.
This is any exothermic reaction.
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13. Reaction :
2KI + Pb(NO3)2 ➵ 2KNO3 + PbI2
Here, PbI2 is yellow precipitate which will turn solution into yellow colour.
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14. Exothermic Reaction
• Energy is produced.
• Takes place in oxidation reactions
Endothermic Reaction
• Energy is consumed.
• Takes place in reduction reaction.
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15. Displacement Reaction
• When one element displaces other from compound.
Double displacement reaction
• When two elements displaces each other from their compound.
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16. Identifiaction :
• Fe + CuSO4(aq) ➵ FeSO4(aq) + Cu(s)
[Displacement Reaction]
• 2H2 + O2 ➵ 2H2O
[Combination Reaction]
Answer:
Ans 1
Explanation:
when quick lime is added to water it reacts virgously with water to produce slaked lime
CaO+H2O-Ca(OH)2+heat