Chemical Reaction And Equations----

      Practice Sheet

Here you will get some practice questions of Chemical Reaction And Equations. 

This question sheet is made for CBSE CLASS 10th students.

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Table Of Content

1.)MCQ on Chemical Reaction And Equations.
2.)Short Answer Questions on Chemical Reaction And Equations.
3.)Balance the Chemical Chemical Reaction And Equations.
4.)Assertion Reason On Chemical Reaction And Equations.
5.)Long Answer Questions on Chemical Reaction And Equations.

Multiple Choice Questions 

1.)Which of the following is an example of a physical change?
a) Burning of wood
b) Rusting of iron
c) Dissolving sugar in water
d) Cooking an egg

Answer: c) Dissolving sugar in water


2.)What is the balanced chemical equation for the reaction between hydrogen gas (H₂) and oxygen gas (O₂) to form water (H₂O)?
a) H₂ + O₂ → H₂O
b) 2H₂ + O₂ → 2H₂O
c) H₂ + O₂ → 2H₂O
d) 2H₂ + 2O₂ → 2H₂O

Answer: d) 2H₂ + 2O₂ → 2H₂O


3.)In a chemical equation, the reactants are usually written on the ___________ side.
a) Left
b) Right
c) Top
d) Bottom

Answer: a) Left


4.)Which of the following is a balanced chemical equation?
a) H₂O + CO₂ → H₂CO₃
b) 2H₂O + CO₂ → H₂CO₃
c) H₂O + CO₂ → 2H₂CO₃
d) H₂O + CO₂ → H₂CO₂

Answer: c) H₂O + CO₂ → 2H₂CO₃


5.)The number placed in front of a chemical formula in a balanced chemical equation is called a ___________.
a) Coefficient
b) Subscript
c) Exponent
d) Prefix

Answer: a) Coefficient


6.)What is the product of the following reaction? Fe + O₂ → Fe₂O₃
a) Iron oxide
b) Oxygen gas
c) Iron(III) oxide
d) Iron(II) oxide

Answer: c) Iron(III) oxide


7.)Which of the following is a decomposition reaction?
a) CH₄ + 2O₂ → CO₂ + 2H₂O
b) 2H₂ + O₂ → 2H₂O
c) 2Na + Cl₂ → 2NaCl
d) 2HgO → 2Hg + O₂

Answer: d) 2HgO → 2Hg + O₂


8.)What is the general formula for a neutralization reaction?
a) A + B → AB
b) A + B → A + B
c) A + B → AB₂
d) Acid + Base → Salt + Water                               


9.)Which of the following is a chemical change?
a) Boiling of water
b) Melting of ice
c) Rusting of iron
d) Freezing of alcohol
Answer: c) Rusting of iron


10.)A chemical equation represents a chemical reaction using:
a) Words
b) Symbols and formulas
c) Numbers and symbols
d) Pictures and diagrams
Answer: b) Symbols and formulas



11.)In a chemical equation, the reactants are written on the:
a) Left-hand side
b) Right-hand side
c) Top side
d) Bottom side
Answer: a) Left-hand side



12.)The number written in front of a chemical formula in a balanced equation is called the:
a) Coefficient
b) Subscript
c) Exponent
d) Index
Answer: a) Coefficient



13.)In a balanced chemical equation, the number of atoms of each element is:
a) Equal on both sides
b) Different on both sides
c) Equal only in some cases
d) Irrelevant in a balanced equation
Answer: a) Equal on both sides



14.)Which of the following is a product of the reaction between hydrochloric acid and sodium hydroxide?
a) Sodium chloride and water
b) Sodium hydroxide and water
c) Sodium chloride and hydrogen gas
d) Sodium chloride and oxygen gas
Answer: a) Sodium chloride and water



15.)Which of the following is an example of a combustion reaction?
a) Burning of wood
b) Rusting of iron
c) Digestion of food
d) Photosynthesis in plants
Answer: a) Burning of wood



16.)The chemical formula for water is:
a) CO2
b) H2O
c) NaCl
d) CH4
Answer: b) H2O



17.)Which of the following represents a decomposition reaction?
a) AB → A + B
b) A + B → AB
c) AB + CD → AD + CB
d) AB + CD → AC + BD
Answer: a) AB → A + B



18.)What is the product of the reaction between magnesium oxide and hydrochloric acid?
a) Magnesium chloride and water
b) Magnesium hydroxide and water
c) Magnesium oxide and water
d) Magnesium chloride and oxygen gas
Answer: a) Magnesium chloride and water



19.)What is the balanced equation for the reaction between sulfuric acid and calcium hydroxide?
a) H2SO4 + Ca(OH)2 → CaSO4 + H2O
b) H2SO4 + Ca(OH)2 → CaSO4 + 2H2O
c) H2SO4 + Ca(OH)2 → CaSO4 + H2
d) H2SO4 + Ca(OH)2 → CaSO4 + H2O + O2
Answer: b) H2SO4 + Ca(OH)2 → CaSO4 + 2H2O



Short Answer questions



Q1: Define a chemical reaction.
A1: A chemical reaction is a process in which one or more substances (reactants) undergo a chemical change to form new substances (products) with different properties.

Q2: What are reactants and products in a chemical equation?
A2: Reactants are the substances that undergo a chemical change, and products are the substances formed as a result of the chemical reaction.

Q3: What is a balanced chemical equation?
A3: A balanced chemical equation has an equal number of atoms of each element on both sides of the equation. It follows the law of conservation of mass.

Q4: What does the arrow (→) represent in a chemical equation?
A4: The arrow (→) in a chemical equation represents the direction of the reaction. It indicates the conversion of reactants into products.

Q5: What are coefficients in a chemical equation?
A5: Coefficients in a chemical equation represent the relative number of molecules or moles of each substance involved in the reaction. They are used to balance the equation.

Q6: State the law of conservation of mass.
A6: The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction. The total mass of the reactants is equal to the total mass of the products.

Q7: Why is it necessary to balance a chemical equation?
A7: Balancing a chemical equation is necessary to satisfy the law of conservation of mass. It ensures that the number of atoms of each element is the same on both sides of the equation.

Q8: What are the different types of chemical reactions?
A8: The different types of chemical reactions include combination reactions, decomposition reactions, displacement reactions, and redox reactions.

Q9: Define exothermic and endothermic reactions.
A9: In an exothermic reaction, heat is released to the surroundings, resulting in a temperature increase. In an endothermic reaction, heat is absorbed from the surroundings, causing a temperature decrease.

Q10: Give an example of a redox reaction.
A10: The reaction of iron with oxygen to form iron oxide (rust) is an example of a redox reaction:
4Fe + 3O2 → 2Fe2O3

Balance the Chemical equations

Q.1)Balance the equation: H2 + O2 -> H2O
Answer: 2H2 + O2 -> 2H2O Q.2)Balance the equation: Mg + O2 -> MgO Answer: 2Mg + O2 -> 2MgO Q.3)Balance the equation: Fe + H2O -> Fe3O4 + H2 Answer: 3Fe + 4H2O -> Fe3O4 + 4H2 Q.4)Balance the equation: Na + Cl2 -> NaCl Answer: 2Na + Cl2 -> 2NaCl Q.5)Balance the equation: NH3 + O2 -> NO + H2O Answer: 4NH3 + 5O2 -> 4NO + 6H2O Q.6)Balance the equation: Al + CuSO4 -> Al2(SO4)3 + Cu Answer: 2Al + 3CuSO4 -> Al2(SO4)3 + 3Cu Q.7)Balance the equation: C2H6 + O2 -> CO2 + H2O Answer: 2C2H6 + 7O2 -> 4CO2 + 6H2O Q.8)Balance the equation: HCl + NaOH -> NaCl + H2O Answer: HCl + NaOH -> NaCl + H2O Q.9)Balance the equation: N2 + H2 -> NH3 Answer: N2 + 3H2 -> 2NH3
Q.10)Balance the equation: Pb(NO3)2 + HCl -> PbCl2 + HNO3 Answer: Pb(NO3)2 + 2HCl -> PbCl2 + 2HNO3 Q.11)Balance the equation: CH4 + O2 -> CO2 + H2O Answer: CH4 + 2O2 -> CO2 + 2H2O Q.12)Balance the equation: KClO3 -> KCl + O2 Answer: 2KClO3 -> 2KCl + 3O2 Q.13)Balance the equation: P4 + O2 -> P2O5 Answer: P4 + 5O2 -> 2P2O5 Q.14)Balance the equation: H2SO4 + Ca(OH)2 -> CaSO4 + H2O Answer: H2SO4 + 2Ca(OH)2 -> CaSO4 + 2H2O Q.15)Balance the equation: C3H8 + O2 -> CO2 + H2O Answer: C3H8 + 5O2 -> 3CO2 + 4H2O Q.16)Balance the equation: FeS + HCl -> FeCl3 + H2S Answer: FeS + 6HCl -> 2FeCl3 + 3H2S Q.17)Balance the equation: C6H12O6 + O2 -> CO2 + H2O Answer: C6H12O6 + 6O2 -> 6CO2 + 6H2O Q.18)Balance the equation: HNO3 + Mg(OH)2 -> Mg(NO3)2 + H2O Answer: 2HNO3 + Mg(OH)2 -> Mg(NO3)2 + 2H2O

Assertion-Reason-----:

1.)Assertion: During a chemical reaction, the total mass of the reactants is equal to the total mass of the products.
Reason: The law of conservation of mass states that mass can neither be created nor destroyed during a chemical reaction.


2.)Assertion: A chemical equation is balanced to satisfy the law of conservation of mass.
Reason: The number of atoms of each element is the same on both sides of a balanced chemical equation.


3.)Assertion: A catalyst increases the rate of a chemical reaction.
Reason: A catalyst provides an alternative pathway with lower activation energy for the reaction to occur.


4.)Assertion: The reactants in a chemical reaction are written on the left side of the chemical equation.
Reason: The reactants are the starting materials that undergo a chemical change to form products.


5.)Assertion: A precipitation reaction is a type of double displacement reaction.
Reason: In a precipitation reaction, an insoluble solid (precipitate) is formed when two aqueous solutions are mixed.


6.)Assertion: Endothermic reactions absorb heat from the surroundings.
Reason: The products of an endothermic reaction have higher energy than the reactants.

7.)Assertion: Combustion reactions involve the reaction of a substance with oxygen, usually producing heat and light.
Reason: Combustion reactions are always exothermic.

8.)Assertion: In a chemical equation, the number of atoms of each element is represented by the coefficients.
Reason: Coefficients are used to balance the equation and ensure that the law of conservation of mass is satisfied.

9.)Assertion: The reaction between an acid and a base is a neutralization reaction.
Reason: In a neutralization reaction, an acid and a base react to form a salt and water.

10.)Assertion: Oxidation and reduction always occur simultaneously in a chemical reaction.
Reason: Oxidation involves the loss of electrons, while reduction involves the gain of electrons.


11.)Assertion: The reactant that is completely used up in a chemical reaction is called the limiting reactant.
Reason: The limiting reactant determines the maximum amount of product that can be formed.


12.)Assertion: A balanced chemical equation can provide information about the ratio of reactants and products in a reaction.
Reason: The coefficients in a balanced chemical equation represent the mole ratio of the substances involved.

Answers

1.)Answer: Both the assertion and reason are correct and are the correct explanation of each other.

2.)Answer: Both the assertion and reason are correct, but the reason is not the correct explanation of the assertion.

3.)Answer: Both the assertion and reason are correct and are the correct explanation of each other.

4.)Answer: Both the assertion and reason are correct and are the correct explanation of each other.

5.)Answer: Both the assertion and reason are correct and are the correct explanation of each other .

6.)Answer: Both the assertion and reason are correct and are the correct explanation of each other.

7.)Answer: Both the assertion and reason are correct and are the correct explanation of each other.

8.)Answer: Both the assertion and reason are correct and are the correct explanation of each other.

9.)Answer: Both the assertion and reason are correct and are the correct explanation of each other.

10.)Answer: Both the assertion and reason are correct, but the reason is not the correct explanation of the assertion.

11.)Answer: Both the assertion and reason are correct and are the correct explanation of each other.

12.)Answer: Both the assertion and reason are correct and are the correct explanation of each other.

Long Answer question 

1. Define a chemical reaction. Provide an example and write its balanced chemical equation.

Ans) A chemical reaction is a process in which one or more substances undergo a transformation to form new substances with different properties. 

Example: Combustion of methane
Balanced Chemical Equation: CH₄ + 2O₂ → CO₂ + 2H₂O

2. What is the law of conservation of mass? Explain with an example.

Ans) The law of conservation of mass states that matter cannot be created or destroyed in a chemical reaction. The total mass of the reactants must be equal to the total mass of the products.

Example: Reaction between iron and sulfur
Balanced Chemical Equation: Fe + S → FeS
In this reaction, the mass of iron and sulfur atoms before the reaction must be equal to the mass of iron sulfide formed after the reaction.

3. Differentiate between a reactant and a product.

Ans) Reactant: A reactant is a substance that undergoes a chemical change in a reaction. It is present before the reaction begins.

Product: A product is a substance that is formed as a result of a chemical reaction. It is obtained after the reaction is completed.

4. What is a balanced chemical equation? Why is it important?

Ans) A balanced chemical equation is an equation in which the number of atoms of each element is equal on both sides of the equation. It represents the stoichiometry of the reaction, indicating the ratios in which reactants combine and products are formed.

Balancing equations is important because it ensures that the law of conservation of mass is obeyed. It provides a clear understanding of the relative quantities of reactants and products involved in a chemical reaction.

5. Explain exothermic and endothermic reactions with examples.

Ans) Exothermic Reaction: An exothermic reaction is a reaction that releases heat energy to its surroundings. The products have less energy than the reactants.

Example: Combustion of wood
Balanced Chemical Equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + heat

Endothermic Reaction: An endothermic reaction is a reaction that absorbs heat energy from its surroundings. The products have more energy than the reactants.

Example: Photosynthesis
Balanced Chemical Equation: 6CO₂ + 6H₂O + sunlight → C₆H₁₂O₆ + 6O₂

6. What is a catalyst? How does it affect a chemical reaction?

Ans) A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It provides an alternative pathway with a lower activation energy for the reaction to occur.

A catalyst affects a chemical reaction by lowering the activation energy required for the reaction to proceed. This increases the rate of the reaction but does not affect the final products or the overall energy change of the reaction.

7. Define combination and decomposition reactions with examples.

Ans) In Combination Reaction: A combination reaction is a type of chemical reaction in which two or more substances combine to form a single product.

Example: Formation of water
Balanced Chemical Equation: 2H₂ + O₂ → 2H₂O

Decomposition Reaction: A decomposition reaction is a type of chemical reaction in which a compound breaks down into two or more simpler substances.

Example: Decomposition of hydrogen peroxide
Balanced Chemical Equation: 2H₂O₂ → 2H₂O + O₂

8. Write the balanced chemical equation for the reaction between sodium hydroxide and hydrochloric acid, and state the type of reaction.

Ans) The balanced chemical equation for the reaction between sodium hydroxide (NaOH) and hydrochloric acid (HCl) is as follows:

NaOH + HCl → NaCl + H2O

This is a neutralization reaction, where an acid reacts with a base to form a salt and water. In this case, sodium hydroxide, a strong base, reacts with hydrochloric acid, a strong acid, to produce sodium chloride (a salt) and water.

9. Write the balanced chemical equation for the reaction between magnesium and hydrochloric acid, and state the type of reaction.

Ans) The balanced chemical equation for the reaction between magnesium (Mg) and hydrochloric acid (HCl) is as follows:

Mg + 2HCl → MgCl2 + H2

This is a single displacement reaction, where magnesium, which is higher in the activity series, displaces hydrogen from hydrochloric acid to form magnesium chloride and hydrogen gas. The magnesium atom loses two electrons to form Mg2+ ions, while the hydrogen ions (H+) from the acid gain electrons to form hydrogen gas (H2).

10. Write the balanced chemical equation for the reaction between iron(III) oxide and carbon monoxide, and state the type of reaction.

Ans) The balanced chemical equation for the reaction between iron(III) oxide (Fe2O3) and carbon monoxide (CO) is as follows:

Fe2O3 + 3CO → 2Fe + 3CO2

This is a redox reaction, specifically a reduction reaction. In this reaction, iron(III) oxide is reduced to iron, and carbon monoxide is oxidized to carbon dioxide. Iron(III) oxide gains electrons and is reduced to elemental iron, while carbon monoxide loses electrons and is oxidized to carbon dioxide.

11. Write the balanced chemical equation for the reaction between calcium oxide and water, and state the type of reaction.

Ans) The balanced chemical equation for the reaction between calcium oxide (CaO) and water (H2O) is as follows:

CaO + H2O → Ca(OH)2

This is a combination reaction, where two or more substances combine to form a single compound. In this case, calcium oxide reacts with water to form calcium hydroxide. The calcium oxide (CaO) reacts with water (H2O), and the resulting compound is calcium hydroxide (Ca(OH)2).

12. Define a chemical reaction and give an example.
Answer: A chemical reaction is a process in which one or more substances undergo a chemical change to form new substances. For example, the reaction between hydrogen gas and oxygen gas to form water is a chemical reaction: 2H2(g) + O2(g) → 2H2O(l).

13. What are reactants and products in a chemical equation? Give an example.
Answer: Reactants are the substances that participate in a chemical reaction and are written on the left side of a chemical equation. Products are the substances formed as a result of the reaction and are written on the right side of the chemical equation. For example, in the reaction: CH4(g) + 2O2(g) → CO2(g) + 2H2O(g), CH4 and O2 are the reactants, while CO2 and H2O are the products.

14. Define a balanced chemical equation. Why is it necessary to balance a chemical equation?
Answer: A balanced chemical equation is one in which the number of atoms of each element is equal on both sides of the equation. It is necessary to balance a chemical equation to satisfy the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction. Balancing the equation ensures that the same number of atoms of each element is present on both sides.

15. Explain the different types of chemical reactions with examples.
Answer:
- Combination reaction: A reaction in which two or more substances combine to form a single product. Example: 2Mg(s) + O2(g) → 2MgO(s).
- Decomposition reaction: A reaction in which a single compound breaks down into two or more simpler substances. Example: 2H2O(l) → 2H2(g) + O2(g).
- Displacement reaction: A reaction in which an element displaces another element in a compound. Example: Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s).
- Double displacement reaction: A reaction in which ions of two compounds exchange places to form two new compounds. Example: AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq).

16. What is the importance of a catalyst in a chemical reaction?
Answer: A catalyst is a substance that speeds up the rate of a chemical reaction without itself being consumed. It provides an alternative reaction pathway with lower activation energy, making the reaction occur more quickly. Catalysts are important as they increase the efficiency of industrial processes, reduce energy requirements, and enable reactions to occur under milder conditions.

17. Explain the terms exothermic and endothermic reactions with examples.
Answer:
- Exothermic reaction: A reaction that releases heat to the surroundings. Example: Combustion of natural gas: CH4(g) + 2O2(g) → CO2(g) + 2H2O(l) + heat.
- Endothermic reaction: A reaction that absorbs heat from the surroundings. Example: Photosynthesis: 6CO2(g) + 6H2O(l) + energy → C6H12O6(aq) + 6O2(g).

18. What is meant by a redox reaction? Provide an example.
Answer: A redox (reduction-oxidation) reaction is a type of chemical reaction in which both oxidation and reduction occur simultaneously. In a redox reaction, there is a transfer of electrons from one substance to another. For example, the reaction of magnesium with hydrochloric acid: Mg