Chemical Reactions MCQs Class-8 Dalal Simplified ICSE Chemistry Solutions Chapter-6, Chemical Reactions Dr Viraf J Dalal Middle School Allied Publishers Solutions. Chapter-6. We Provide Step by Step Solutions to Correct answer, Fill in the blanks, Match the following, Differentiate between the following of Dr Viraf J Dalal Middle School Chemistry Allied Publishers. Visit official Website CISCE for detail information about ICSE Board Class-8.
Chemical Reactions MCQs Class-8 Dalal Simplified ICSE Chemistry Solutions Chapter-6
| Board | ICSE |
| Class | 8th |
| Subject | Chemistry |
| Book Name | Dalal New Simplified |
| Chapter-6 | Chemical Reactions |
| Unit-1 | Chemical Reactions |
| Topic | Solution of exercise MCQs |
| Session | 2023-24 |
Objective Types Questions
Chemical Reactions MCQs Class-8 Dalal Simplified ICSE Chemistry Solutions Chapter-6
Question: 1. Select the correct answer from A, B, C, D and E for each statement given below :
A: Iron B: Carbonic acid C: Hydrogen D: Oxygen E: Carbon monoxide
1. The product formed during direct combination reaction of carbon dioxide and water
2. The neutral gas obtained on thermal decomposition of potassium nitrate.
3. The displaced product of the displacement reaction of sodium with cold water.
4. The catalyst used in the catalytic reaction involving the reactants nitrogen & hydrogen,
5. A neutral oxide which does not react with an acid or a base to give salt & water.
Answer:
| 1. The product formed during direct combination reaction of carbon dioxide and water | B: Carbonic acid |
| 2. neutral gas obtained on thermal decomposition of potassium nitrate. | D: Oxygen |
| 3. The displaced product of the displacement reaction of sodium with cold water. | C: Hydrogen |
| 4. catalyst used in the catalytic reaction involving the reactants nitrogen & hydrogen, | A: Iron |
| 5. A neutral oxide which does not react with an acid or a base to give salt & water. | E: Carbon monoxide |
Question: 2. Complete the statements by filling in the blank with the correct word:
1. Direct combination reaction of phosphorus pentoxide with water gives __H3PO4__ [H3PO3/H3PO4].
2. Decomposition of silver salts in the presence of sunlight is an example of __photochemical decomposition__ (double decomposition/ photochemical decomposition)
3. The element molybdenum used in the reaction of nitrogen with hydrogen at elevated temperatures is an example of a __promoter__ (promoter/ catalyst)
4. The reaction of coke with the stream to give water gas is an example of an __endothermic__ (exothermic/ endothermic) reaction.
5. The metal which reacts with stream and the reaction is reversible is __iron__ (calcium/ iron)
Question: 3. Give a balanced equation for each of the following types of reactions :
1. a thermal decomposition reaction in which a compound decomposes to give two new compounds.
2. A reaction of direct combination i.e. synthesis in which two gases combine to give another gas – which turns lime water milky.
3. a thermal decomposition reaction in which a metallic nitrate decomposes to give – a basic oxide
4. A catalytic, reversible, exothermic reaction.
5. A displacement reaction in which a metal above hydrogen in the reactivity series, displaces another metal from the solution of its compound.
Answer:
Question: 4. Differentiate between the following:
1. Thermal decomposition & thermal dissociation
2. Neutralization reaction & a precipitation reaction
3. Electrolytic decomposition & photochemical decomposition
4. A catalyst & a promoter
5. An acidic oxide & a basic oxide
Answer:
Difference between thermal decomposition & thermal dissociation:
| Thermal decomposition | Thermal dissociation |
|---|---|
| A chemical reaction in which a compound decomposes to give two new elements / a new compound & an element / two new compounds on application of heat without any recombination on cooling is called a thermal decomposition reaction. | A reversible decomposition reaction brought about only by heat is called thermal dissociation reaction. |
| Thermal decomposition is an irreversible reaction. | Thermal dissociation is a reversible decomposition reaction. |
| For example: CaCO3 ⟶ CaO + CO2 |
For example: NH4Cl ⇌ NH3 + HCl |
Difference between Neutralization reaction & a precipitation reaction:
| Neutralization reaction | Precipitation reaction |
|---|---|
| A reaction between two compounds – base and acid to give two new compounds – salt and water – by interchange of radicals is called a Neutralization reaction. | A reaction between two compounds in aqueous solution state to give two new compounds one of which is insoluble (precipitate) is called a Precipitation reaction. |
| For example: NaOH + HCl ⟶ NaCl + H2O |
For example: Pb(NO3)2 + 2NaCl ⟶ 2NaNO3 + PbCl2 |
Difference between Electrolytic decomposition & photochemical decomposition:
| Electrolytic decomposition | Photochemical decomposition |
|---|---|
| A decomposition reaction which is brought about by passage of electric current is known as Electrolytic decomposition. | A decomposition reaction which occurs in the presence of light is known as Photochemical decomposition. |
| For example: 2H2O ⟶ 2H2 + O2 (On Passage of Electric Current) |
For example: 2AgCl ⟶ 2Ag + Cl2 |
Difference between a catalyst & a promoter:
| Catalyst | Promoter |
|---|---|
| A catalyst is used to alter the rate of the reaction but it does not take part in the reaction. | A promoter is a substance which is added to the catalyst to increase its efficiency. |
Difference between an acidic oxide & a basic oxide:
| Acidic oxide | Basic oxide |
|---|---|
| Acidic oxide are oxides of non-metals e.g. SO2, CO2 | Basic oxide are oxides of metals e.g. K2O, CaO |
| react with water to give an acid. | React with water to give a base. |
| React with bases [alkalis] to give salt and water | react with acids to give salt and water. |
Question: 5. Match the chemical reactions in List I with the appropriate answer in List II:
| List I | List II |
| 1. XY ⇌ heat X + Y | A: Displacement reaction |
| 2. XY ⟶ X + Y | B: Double decomposition |
| 3. X + Y − + A + B − ⟶ X + B − + A + Y − | C: Endothermic reaction |
| 4. X + YZ ⟶ XZ + Y | D: Thermal dissociation |
| 5. X + Y → heat XY − Δ | E: Decomposition reaction |
Answer:
| List I | List II |
| 1. XY ⇌ heat X + Y | A: Thermal dissociation |
| 2. XY ⟶ X + Y | B: Decomposition reaction |
| 3. X + Y − + A + B − ⟶ X + B − + A + Y − | C: Double decomposition |
| 4. X + YZ ⟶ XZ + Y | D: Displacement reaction |
| 5. X + Y → heat XY − Δ | E: Endothermic reaction |
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