Chemical Reactions and Equations For Class 10 Chemistry Important Questions are available in this page. Students can learn MCQ, Equations practice in the easiest way.
Q 1 – Magnesium ribbon is rubbed before burning because it has a coating of
(a) basic magnesium carbonate
(b) basic magnesium oxide
(c) basic magnesium sulphide
(d) basic magnesium chloride
(a) basic magnesium carbonate
Q 2 – Which of the following are exothermic processes?
(i) Reaction of water with quick lime
(ii) Dilution of an acid
(iii) Evaporation of water
(iv) Sublimation of camphor (crystals)
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (i) and (iv)
(a) (i) and (ii)
Q 3 – Oxidation is a process which involves
(a) addition of oxygen
(b) addition of hydrogen
(c) removal of oxygen
(d) removal of hydrogen
(a) addition of oxygen
Q 4 – Which among the following statement(s) is (are) true?
Exposure of silver chloride to sunlight for a long duration turns grey due to
(i) the formation of silver by decomposition of silver chloride
(ii) sublimation of silver chloride
(iii decomposition of chlorine gas from silver chloride
(iv) oxidation of silver chloride
(a) (i) only
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (iv) only
(a) (i) only
Q 5 – MnO2 + 4HCl → 2 + 2H2O + Cl2
Identify the substance oxidized in the above . equation.
(a) MnCl2
(b) HCl
(c) H2O
(d) MnO2
(d) MnO2
Q 6 – Which of the following is an endothermic process?
(a) Dilution of sulphuric acid
(b) Sublimation of dry ice
(c) Condensation of water vapours
(d) Respiration in human beings
(b) Sublimation of dry ice
Q 7 – 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
(b) Lead acetate
Q 8 – Select the oxidising agent for the following reaction:
H2S + I2 > 2HI + S
(a) I2
(b) H2S
(C) HI
(d) S
(a) I2
Q 9 – The condition produced by aerial oxidation of fats and oils in foods marked by unpleasant smell and taste is called:
(a) antioxidation
(b) reduction
(c) rancidity
(d) corrosion
(c) rancidity
Q 10 – Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is:
(a) 1 : 1
(b) 2:1
(c) 4:1
(d) 1:2
(b) 2:1
Q 11 – In electrolysis of water, why is the volume of gas collected over one electrode double that of gas collected over the other electrode.
Water contains hydrogen and oxygen in the ratio of 2 : 1, that is why volume of H2 is double than that of oxygen.
Q 12 – State one industrial application of reduction process.
It is used in the extraction of metals e.g.,
ZnO(s) + C(s) Zn(s) + CO2 (g)
Q 13 – Which one is a chemical change: Rusting of iron or melting of iron?
Rusting of iron is a chemical change.
Q 14 – Hydrogen being a highly inflammable gas and oxygen being a supporter of combustion, yet water, a compound made up of hydrogen and oxygen is used to extinguish fire. Why?
H2 O is a compound constituted of hydrogen of oxygen elements and being a compound it has different properties as compared to its constituting elements.
Q 15 – If copper metal is heated over a flame it develops a coating. What is the colour and composition of coating?
Black coloured coating is formed. It is a due to formation of copper oxide.
Q 16 – Write a balanced chemical equation to represent the following reaction: carbon monoxide reacts with hydrogen gas at 340 atm to form methyl alcohol.
CO(g) + 2H2 (g) atm CH3 OH(l)
Q 17 – State the main difference between endothermic reaction and an exothermic reaction.
In endothermic reaction, heat is absorbed. In exothermic reaction, heat is evolved.
Q 18 – Define oxidation and reduction.
Oxidation is a process in which oxygen is added or loss of electrons take place. Reduction is a process in which hydrogen is added or gain of electrons takes place.
Q 19 – On what basis is a chemical reaction balanced?
Chemical equation is balanced on the basis of law of conservation of mass.
Q 20 – Write balanced chemical equation for the following reactions:
(a) Hydrogen sulphide burns in air to give water andsulphur dioxide.
(b) Barium chloride reacts in aqueous solution with zinc sulphate to give zinc chloride and barium sulphate.
(a) 2H2 S(g) + 3O2 (g) →2H2 O(l) + 2SO2 (g)
(b) BaCl (aq) + ZnSO(aq) → BaSO4 (s) + ZnCl2 (aq)
Q 21 – Name the reducing agent in the following reaction:
3MnO2 + 4A1 → 3Mn + Al2 O3
State which is more reactive, Mn or Al and Why?
Al is the reducing agent. Al is more reactive than Mn. Reason: It is because Al is displacing Mn from MnO2 .
Q 22 – “We need to balance a skeleton chemical equation”. Give reason to justify the statement.
We must balance a skeletal equation so as to ensure that the reaction follows ‘Law of conservation of mass’.
The total mass of reactants must be equal to the total mass of products, that is why all reactions should he balanced.
Q 23 – Identify the type of each of the following reactions:
(a) A reaction in which a single product is formed from two ormore reactants.
(b) The reaction mixture becomes warm.
(c) An insoluble substance is formed.
(d) External surface of the container in which reaction takes place becomes cold.
(a) Combination reaction
(b) Exothermic reaction
(c) Precipitation reaction (Double displacement reaction)
(d) Endothermic reaction
Q 24 – A solution of potassium chloride when mixed with silver nitrate solution, an insoluble white substance is formed.
Write the chemical reaction involved and also mention the type of reaction.
AgNO3 (aq) + KCl(aq) →AgCl(s)+KNO3 (aq)
(White ppt.)
It is a double displacement reaction.
Q 25 – What is redox reaction? When a magnesium ribbon burns in air with a dazzling flame and forms a white ash, is magnesium oxidised or reduced. Why?
Redox reaction is a reaction in which oxidation and reduction takes place simultaneously. Mg is getting oxidised because it is gaining oxygen to form magnesium oxide.
Q 26 – Identify the type of chemical reaction in the following statement and define each of them:
- Digestion of food inour body.
- Rusting of iron.
- Heating of manganese dioxide with aluminium powder.
- Blue colour of copper sulphate solution disappears when iron filings are added to it.
- Dilute hydrochloric acid is added to sodium hydroxide solution to form sodium chloride and water.
- Decomposition reaction: It is a process in which a compound is broken down into simple substances.
- Oxidation: The process in which oxygen is added or electrons are lost.
- Displacement reaction: The reaction in which a more reactive element can displace a less reactive element from its salt solution. Oxidation and Reduction are taking place simultaneously in rusting of iron.
- Displacement reaction: The reaction in which a more reactive element can displace a less reactive element.
- Neutralisation reaction: The reaction in which acid reacts with base to form salt and water.
Q 27 – Complete the following equation:
Q 28 – We store silver chloride in a dark coloured bottle because it is
(a) a white solid
(b) undergoes redox reaction
(c) to avoid action by sunlight
(d) none of the above8
(c) to avoid action by sunlight
Q 29 – Dilute hydrochloric acid is added to granulated zinc taken in a test tube. The following observations are recorded. Point out the correct observation.
(a) The surface of metal becomes shining
(b) The reaction mixture turns milky
(c) Odour of a pungent smelling gas is recorded
(d) A colourless and odourless gas is evolved
(d) A colourless and odourless gas is evolved
Q 30 – Which among the following is (are) double displacement reaction(s)?
(i) Pb + CuCl → PbCl2 + Cu
(ii) Na2SO4 + BaCl2 → BaSO4 + 2NaCl
(iii) C + O2 → CO
(iv) CH + 2O → CO2 + 2H2O
(a) (i) and (iv)
(b) (ii) only
(c) (i) and (ii)
(d) (iii) and (iv)
(b) (ii) only
Q 31 – On immersing an iron nail in CuSO4 solution for few minutes, you will observe
(a) no reaction takes place
(b) the colour of solution fades away
(c) the surface of iron nails acquire a black coating
(d) the colour of solution changes to green
(d) the colour of solution changes to green
Q 32 – An element X on exposure to moist air turns reddish-brown and a new compound Y is formed. The substance X and Y are
(a) X = Fe, Y = Fe2O3
(b) X = Ag, Y = Ag2S
(c) X = Cu, Y = CuO
(d) X = Al, Y = Al2O3
(a) X = Fe, Y = Fe2O3
Q 33 –
| Column I | Column II |
| (a) Combination reaction | (p) Synthesis |
| (b) Oxidation of iron | (q) Splitting-up of reactants |
| (c) Displacement reaction | (r) Combustion |
| (d) Decomposition | (s) Substitution |
| Column I | Column II |
| (a) Combination reaction | (p) Synthesis |
| (b) Oxidation of iron | (r) Combustion |
| (c) Displacement reaction | (s) Substitution |
| (d) Decomposition | (q) Splitting-up of reactants |
Q 34 – A teacher gave two test tubes to the students, one containing water and the other containing sodium hydroxide. She asked them to identify the test tube containing sodium hydroxide solution. Which one of the following can be used for the identification?
(a) Blue litmus
(b) Red litmus
(c) Sodium carbonate solution
(d) Dilute hydrochloric acid
(b) Red litmus
Q 35 – 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)
(c) (i) and (iii)
Q 36 – The following reaction is used for the preparation of oxygen gas in the laboratory:
Which of the following statement about the reaction is correct?
(a) It is a decomposition reaction and endothermic in nature.
(b) It is a combination reaction.
(c) It is a decomposition reaction and accompanied by release of heat.
(d) It is a photochemical decomposition reaction and exothermic in nature.
(a) It is a decomposition reaction and endothermic in nature.
Q 37 – Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is
(a) 1 : 1
(b) 2 : 1
(c) 4 : 1
(d) 1 : 2
(b) 2 : 1
Q 38 – For the given reaction, match column I with column II and mark the correct option from the codes given below.
Fe2O3 + xCO → yFe + xCO2
| Column I | Column II |
| (a) Oxidising agent | (p) 2 |
| (b) Reducing agent | (q) 3 |
| (c) x | (r) Fe2O3 |
| (d) y | (s) CO |
(A) (a)-(s), (b)-(r), (c)-(q), (d)-(p)
(B) (a)-(s), (b)-(r), (c)-(p), (d)-(q)
(c) (a)-(r), (b)-(s), (c)-(q), (d)-(p)
(D) (a)-(r), (b)-(s), (c)-(p), (d)-(q)
(c) (a)-(r), (b)-(s), (c)-(q), (d)-(p)
Q 39 – Silver article turns black when kept in the open for a few days due to formation of
(a) H2S
(b) AgS
(c) AgSO4
(d) Ag2S
(d) Ag2S
Q 40 – Which of the following is Not True with respect to the neutralisation reaction?
(a) Salt is formed.
(b) Reaction occurs between an acid and a base.
(c) Reactive element displaces less reactive element.
(d) Reactants are in gaseous state.
(d) Reactants are in gaseous state.
Q 41 – 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)
(d) (ii) and (iv)
Q 42 –Hydrogen peroxide is stored in coloured bottles. Explain the reason for the same ?
This is done in order to cut off light because hydrogen peroxide decomposes into water and oxygen in the presence of light.
Q 43 –What changes in the colour of iron nails and copper sulphate solution can one observe after keeping the iron nails dipped in copper sulphate solution for about 30 minutes ?
When magnesium ribbon burns in air, it combines with the oxygen to form magnesium oxide.
2Mg(s) + O2(g) → 2MgO(s)
Q 44 – Identify the reducing agent in the following reactions.
(a) 4NH3 + 5O2 → 4NO + 6H2O
(b) H2O + F2 → HF + HOF
(c) Fe2O3 + 3CO → 2Fe + 3CO2
(d) 2H2 + O2 → 2H2O
Q 44 – What happens when magnesium ribbon burns in air?
Iron nails become brownish in colour and the blue colour of copper sulphate solution fades. This is because iron displaces copper from copper sulphate solution and forms ferrous sulphate which is light green in colour.
Q 45 – Give reasons :
(a) Aluminium is a reactive metal but is still used for packing food articles.
(b) Red litmus paper turns blue when touched with aqueous solution of magnesium oxide.
(a) On exposure to air, aluminium forms a hard protective layer of aluminium oxide
(AI2O3 ) which prevent further oxidation.
(b) Magnesium oxide is an oxide of a metal, so, it is basic in nature. Due to its basic
character it turns red litmus paper blue when touched with its aqueous solution.
Q 46 – Write the balanced chemical equations for the following reactions and identify the type of reaction in each case.
(i) Nitrogen gas is treated with hydrogen gas in the presence of a catalyst at 773 K to form ammonia gas.
(ii) Sodium hydroxide solution is treated with acetic acid to form sodium acetate and water.
(iii) Ethanol is warmed with ethanoic acid to form ethyl acetate in the presence of concentrated H2SO4 .
(iv) Ethene is burnt in the presence of oxygen to form carbon dioxide, water and releases heat and light.
