Class 10 Exam  >  Class 10 Notes  >  Chemistry for Class 10  >  Assertion & Reason Type Questions: Chemical Reactions & Equations - 2

Class 10 Science Chapter 1 Assertion and Reason Questions - Chemical Reactions and Equations

Direction: Each of these questions contains an Assertion followed by Reason. Read them carefully and answer the question on the basis of following options. You have to select the one that best describes the two statements.
Question 1:
Assertion: Stannous chloride is a powerful oxidising agent which oxidises mercuric chloride to mercury. 
Reason: Stannous chloride gives grey precipitate with mercuric chloride, but stannic chloride does not do so.
(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If Assertion is incorrect but Reason is correct.

Correct Answer is Option (c)
Stannous chloride SnCl2 is a strong reducing agent. It first reduces mercuric chloride (HgCl2) to Mercurous Chloride (greyish) and finally to mercury. 

SnCl+ 2HgCl2 → Hg2Cl2 + SnCl2

HgCl2 + SnCl2  →2Hg + SnCl4 

So, in above reaction, stannous Chloride is acting as reducing agent that reduces Hg(II) toHg(I) and then Hg(0).


Question 2:
Assertion: In a reaction.
Zn (s) + CuSO4 (aq) → ZnSO(aq)+ Cu (s)
Zn is a reductant but itself get oxidized.
Reason: In a redox reaction, oxidant is reduced by accepting electrons and reductant is oxidized by losing electrons.
(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If Assertion is incorrect but Reason is correct.

Correct Answer is Option (a)
Reducing agent is an element or compound that loses an electron to an electron recipient in a redox chemical reaction. A reducing agent is thus oxidized  when it loses electrons in the redox reaction. Reducing agents "reduce" oxidizing agents. Oxidizers "oxidize" reducers


Question 3:
Assertion: The balancing of chemical equations is based on law of conservation of mass. 
Reason: Total mass of reactants is equal to total mass of products.
(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If Assertion is incorrect but Reason is correct.

Correct Answer is Option (a)
The balancing of chemical equations is based on law of conservation of mass. The Law of conservation of mass states that mass can be neither created nor destroyed in a chemical reaction. 

Total mass of reactants is equal to total mass of products. 

Thus, both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

Example of law of conservation of massExample of law of conservation of mass


Question 4:
Assertion (A): A chemical reaction becomes faster at higher temperatures.
Reason (R): At higher temperatures, molecular motion becomes more rapid.

(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If Assertion is incorrect but Reason is correct.

Correct Answer is Option (a)
Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A). A chemical reaction becomes faster at higher temperatures because at high temperature, the movement of particles are greater.


Question 5:
Assertion (A): To dilute sulphuric acid, acid is added to water and not water to acid.
Reason (R): Specific heat of water is quite large.
(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If Assertion is incorrect but Reason is correct.

Correct Answer is Option (a)
Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
The mixing of water to an acid is highly exothermic in nature. If water is added to an acid it produces very large amount of heat which can break the container and some times even causes burnings. So it is advised to add concentrated acid to water very slow manner.


Question 6:
Assertion(A): Brown fumes are produced when lead nitrate is heated. 
Reason (R): Nitrogen dioxide gas is produced as a by product due to the decomposition of lead nitrate.
(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If Assertion is incorrect but Reason is correct.

Correct Answer is Option (a)
When lead nitrate is heated strongly, NO and O. In this decomposition reaction, the colourless compound lead nitrate forms a yellow compound, lead monoxide, and brown fumes of nitrogen dioxide gas are evolved.


Question 7:
Assertion(A): Pungent smelling gas is produced when sulphur burns in air. 
Reason (R): Sulphur trioxide is formed on reaction of sulphur with oxygen.
(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If Assertion is incorrect but Reason is correct.

Correct Answer is Option (a)
Since Reason mentioned is false because when sulphur burns in air then sulphur reacts with oxygen to form sulphur dioxide which gives the pungent smell.


Question 8:
Assertion: The following chemical equation,
2C6H6 + 7/2O2 → 4CO2 + 3H2O
is a balanced chemical equation.
Reason: In a balanced chemical equation, the total number of atoms of each element may or may not equal on both side of the equation.
(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion. 
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If Assertion is incorrect but Reason is correct.

Correct Answer is Option (c)
Both Assertion and Reason are false. Both Assertion and Reason are false. In a balanced chemical equation, the total number of atoms of each element are equal on both sides of the equation. The correct balanced chemical equation is, 2C2H6 + 7O→ 4CO2 + 6H2O


Question 9:
Assertion: In the following chemical equation,
CuO (s) + Zn (s) → ZnO (s)+ Cu (s)
Zinc is getting oxidised and copper oxide is getting reduced. 
Reason: The process in which oxygen is added to a substance is called oxidation whereas the process in which oxygen is removed from a substance is called reduction.
(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion. 
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If Assertion is incorrect but Reason is correct.

Correct Answer is Option (a)
If both Assertion and Reason are true and Reason is the correct explanation of Assertion. Because the reaction involves both oxidation and reduction in which, CuO is reduced to Cu and Zn is oxidised to ZnO.


Question 10:
Assertion (A): Sodium metal is stored under Kerosene. 
Reason (R): Metallic sodium melts when exposed to air.
(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion. 
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If Assertion is incorrect but Reason is correct.

Correct Answer is Option (c)
Assertion (A) is true but reason (R) is false. Sodium is a very reactive metal. It is kept in kerosene to prevent it from coming in contact with oxygen and moisture present. If this happens, it will react with the moisture present in air and form sodium hydroxide. This is a strongly exothermic reaction, and lot of heat is generated.

The document Class 10 Science Chapter 1 Assertion and Reason Questions - Chemical Reactions and Equations is a part of the Class 10 Course Chemistry for Class 10.
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FAQs on Class 10 Science Chapter 1 Assertion and Reason Questions - Chemical Reactions and Equations

1. What is the difference between a chemical reaction and a chemical equation?
Ans. A chemical reaction refers to the process in which one or more substances are transformed into different substances with new properties. On the other hand, a chemical equation is a symbolic representation of a chemical reaction, showing the reactants and products involved, along with their respective stoichiometric coefficients.
2. How can we determine the type of chemical reaction based on a chemical equation?
Ans. The type of chemical reaction can be determined based on the nature of the reactants and products involved. Some common types of reactions include synthesis, decomposition, combustion, displacement, and double displacement. By analyzing the chemical equation and observing the changes in elements and compounds, we can identify the type of reaction.
3. Why is balancing a chemical equation important?
Ans. Balancing a chemical equation is important because it ensures that the law of conservation of mass is obeyed. According to this law, mass is neither created nor destroyed during a chemical reaction. By balancing the equation, we ensure that the number of atoms of each element is the same on both sides of the equation, representing a balanced reaction.
4. How can we balance a chemical equation?
Ans. To balance a chemical equation, we can follow the following steps: 1. Identify the unbalanced elements and count the number of atoms on both sides of the equation. 2. Start by adjusting the coefficients of the compounds containing the unbalanced elements, ensuring that the number of atoms is equal on both sides. 3. Continue adjusting coefficients until all elements are balanced. 4. Finally, check to ensure that the equation is completely balanced by counting the number of atoms of each element.
5. What are the limitations of chemical equations?
Ans. Some limitations of chemical equations include: 1. They do not provide information about the reaction rate or the mechanism by which the reaction occurs. 2. They do not provide information about the physical state of the reactants and products. 3. They do not provide information about the energy changes that occur during the reaction. 4. They do not provide information about the conditions required for the reaction to occur. Overall, chemical equations provide a simplified representation of a chemical reaction and may not capture all the complexities and details associated with it.
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