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Chemistry Practice Questions

NCERT Class X Chapter 1: Chemical Reactions and Equations

Created & Curated By S.K. Sinha

Section A: Questions
Q1.
Which of the following represents a balanced chemical equation?
(A) Mg + O2 β†’ MgO
(B) 2Mg + O2 β†’ 2MgO
(C) Mg + 2O2 β†’ MgO
(D) 3Mg + O2 β†’ 3MgO
Q2.
The reaction CaCO3 β†’ CaO + CO2 is an example of:
(A) Combination reaction
(B) Decomposition reaction
(C) Displacement reaction
(D) Double displacement reaction
Q3.
In the reaction Fe + CuSO4 β†’ FeSO4 + Cu, iron acts as:
(A) Oxidizing agent
(B) Reducing agent
(C) Catalyst
(D) Neither oxidizing nor reducing agent
Q4.
The coefficient of H2SO4 in the balanced equation:
Al + H2SO4 β†’ Al2(SO4)3 + H2 is:
(A) 2
(B) 3
(C) 4
(D) 6
Q5.
Which of the following is a precipitation reaction?
(A) NaOH + HCl β†’ NaCl + H2O
(B) AgNO3 + NaCl β†’ AgCl + NaNO3
(C) Zn + H2SO4 β†’ ZnSO4 + H2
(D) CaO + H2O β†’ Ca(OH)2
Q6.
The oxidation state of chromium in K2Cr2O7 is:
(A) +3
(B) +4
(C) +6
(D) +7
Q7.
In the reaction 2KClO3 β†’ 2KCl + 3O2, the type of reaction is:
(A) Combination
(B) Decomposition
(C) Single displacement
(D) Double displacement
Q8.
The balanced equation for the reaction between aluminum and oxygen is:
(A) Al + O2 β†’ AlO2
(B) 2Al + 3O2 β†’ 2Al2O3
(C) 4Al + 3O2 β†’ 2Al2O3
(D) Al + O β†’ AlO
Q9.
Which of the following is NOT a sign of a chemical reaction?
(A) Change in color
(B) Evolution of gas
(C) Change in state
(D) Formation of precipitate
Q10.
The reaction BaCl2 + H2SO4 β†’ BaSO4 + 2HCl is an example of:
(A) Displacement reaction
(B) Combination reaction
(C) Double displacement reaction
(D) Decomposition reaction
Q11.
In the reaction H2 + Cl2 β†’ 2HCl, the molar ratio of H2:Cl2:HCl is:
(A) 1:1:1
(B) 1:1:2
(C) 2:1:2
(D) 1:2:2
Q12.
The process of coating iron with zinc is called:
(A) Galvanization
(B) Electroplating
(C) Anodization
(D) Vulcanization
Q13.
Which of the following equations represents a redox reaction?
(A) CaCO3 + 2HCl β†’ CaCl2 + CO2 + H2O
(B) AgNO3 + NaCl β†’ AgCl + NaNO3
(C) Zn + CuSO4 β†’ ZnSO4 + Cu
(D) NaOH + HCl β†’ NaCl + H2O
Q14.
The balanced equation for the combustion of methane is:
(A) CH4 + O2 β†’ CO2 + H2O
(B) CH4 + 2O2 β†’ CO2 + 2H2O
(C) 2CH4 + 3O2 β†’ 2CO2 + 4H2O
(D) CH4 + 3O2 β†’ CO2 + 2H2O
Q15.
In the reaction 2FeCl3 + H2S β†’ 2FeCl2 + 2HCl + S, the reducing agent is:
(A) FeCl3
(B) H2S
(C) HCl
(D) S
Q16.
The formation of water from hydrogen and oxygen is a:
(A) Endothermic reaction
(B) Exothermic reaction
(C) Photochemical reaction
(D) Electrochemical reaction
Q17.
The reaction NH4Cl + NaOH β†’ NH3 + NaCl + H2O is an example of:
(A) Combination reaction
(B) Decomposition reaction
(C) Single displacement reaction
(D) Double displacement reaction
Q18.
The white precipitate formed when CO2 is passed through lime water is:
(A) CaCO3
(B) Ca(OH)2
(C) CaO
(D) Ca(HCO3)2
Q19.
In the reaction C + O2 β†’ CO2, carbon is:
(A) Oxidized
(B) Reduced
(C) Neither oxidized nor reduced
(D) Both oxidized and reduced
Q20.
The reaction CaO + H2O β†’ Ca(OH)2 is called:
(A) Hydration
(B) Hydrolysis
(C) Slaking
(D) Neutralization
Q21.
The number of molecules in the balanced equation P4 + 5O2 β†’ P4O10 is:
(A) 5
(B) 6
(C) 7
(D) 10
Q22.
The reaction 2H2O2 β†’ 2H2O + O2 is catalyzed by:
(A) MnO2
(B) Fe2O3
(C) Al2O3
(D) CuO
Q23.
In the reaction 2Na + Cl2 β†’ 2NaCl, the substance that gets reduced is:
(A) Na
(B) Cl2
(C) NaCl
(D) None of these
Q24.
The reaction AgBr β†’ Ag + Br2 (in presence of light) is an example of:
(A) Thermal decomposition
(B) Electrolytic decomposition
(C) Photolytic decomposition
(D) Catalytic decomposition
Q25.
The coefficient of O2 in the balanced equation for the combustion of ethane (C2H6) is:
(A) 5
(B) 6
(C) 7
(D) 8
Section B: Answers
Question Answer
Q1 (B)
Q2 (B)
Q3 (B)
Q4 (B)
Q5 (B)
Q6 (C)
Q7 (B)
Q8 (C)
Q9 (C)
Q10 (C)
Q11 (B)
Q12 (A)
Q13 (C)
Q14 (B)
Q15 (B)
Q16 (B)
Q17 (D)
Q18 (A)
Q19 (A)
Q20 (C)
Q21 (C)
Q22 (A)
Q23 (B)
Q24 (C)
Q25 (C)
Section C: Solutions
Q1.
Equal atoms on both sides: 2 Mg, 2 O atoms.
Q2.
Single compound breaks into two products.
Q3.
Fe loses electrons (oxidized), hence reducing agent.
Q4.
Balanced: 2Al + 3H2SO4 β†’ Al2(SO4)3 + 3H2
Q5.
AgCl is insoluble white precipitate.
Q6.
K = +1, O = -2; 2(+1) + 2x + 7(-2) = 0; x = +6
Q7.
KClO₃ breaks into KCl and Oβ‚‚.
Q8.
Balance atoms: 4 Al, 6 O on each side.
Q9.
State change is physical, not chemical.
Q10.
Ions exchange partners: Ba²⁺ + SO₄²⁻ β†’ BaSOβ‚„
Q11.
Coefficients show 1:1:2 ratio.
Q12.
Zinc coating prevents rusting of iron.
Q13.
Zn oxidized (0 β†’ +2), Cu reduced (+2 β†’ 0).
Q14.
1 CHβ‚„ needs 2 Oβ‚‚ for complete combustion.
Q15.
Hβ‚‚S loses electrons (S: -2 β†’ 0).
Q16.
Heat released during bond formation.
Q17.
NH₄⁺ exchanges with Na⁺.
Q18.
Ca(OH)β‚‚ + COβ‚‚ β†’ CaCO₃ + Hβ‚‚O
Q19.
C gains oxygen (0 β†’ +4 oxidation state).
Q20.
Quicklime + water = slaked lime.
Q21.
Count molecules: 1 Pβ‚„ + 5 Oβ‚‚ + 1 Pβ‚„O₁₀ = 7
Q22.
MnOβ‚‚ speeds Hβ‚‚Oβ‚‚ decomposition.
Q23.
Clβ‚‚ gains electrons (0 β†’ -1).
Q24.
Light energy breaks AgBr bonds.
Q25.
Balanced: 2C2H6 + 7O2 β†’ 4CO2 + 6H2O

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