(A) Why do we balance a chemical equation? Name and state the law that suggests the balancing of a chemical equation? Balance the following chemical equation:
OR
(B) Define a precipitation reaction. Give its example and also express the reaction that occurs in the form of a balanced chemical equation.
(A) Why do we balance a chemical equation? Name and state the law that suggests the balancing of a chemical equation? Balance the following chemical equation:
OR
(B) Define a precipitation reaction. Give its example and also express the reaction that occurs in the form of a balanced chemical equation.
(A) We balance a chemical equation to satisfy the law of conservation of mass, which states that mass can neither be created nor destroyed in a chemical reaction. The law that suggests the balancing of a chemical equation is the law of conservation of mass.
(B) A precipitation reaction is a type of chemical reaction in which an insoluble solid (precipitate) is formed from a solution. For example, when a solution of lead nitrate is added to a solution of potassium iodide, a yellow precipitate of lead iodide is formed.
Marking Scheme
- 1(A) 1 mark for explaining the law of conservation of mass
- 2(A) 1 mark for balancing the chemical equation
- 3(B) 1 mark for defining a precipitation reaction
- 4(B) 1 mark for providing an example and expressing the reaction in the form of a balanced chemical equation
Hint
(A) Recall the law of conservation of mass and its significance in balancing chemical equations. (B) Understand the definition of a precipitation reaction and provide an example.
Quick Oral Answer
The law of conservation of mass states that mass can neither be created nor destroyed in a chemical reaction. This law is the basis for balancing chemical equations. A precipitation reaction is a type of chemical reaction in which an insoluble solid (precipitate) is formed from a solution.
Analysis & Explanation
(A) The law of conservation of mass is a fundamental principle in chemistry that states that mass can neither be created nor destroyed in a chemical reaction. This law is the basis for balancing chemical equations.
(B) A precipitation reaction is a type of chemical reaction in which an insoluble solid (precipitate) is formed from a solution. The reaction between lead nitrate and potassium iodide is an example of a precipitation reaction.
Common Mistakes
- 1Forgetting to balance the chemical equation
- 2Not providing a correct example of a precipitation reaction
Interesting Facts
The law of conservation of mass was first proposed by Antoine Lavoisier in the 18th century.
Precipitation reactions are commonly used in chemistry to prepare insoluble salts.
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Frequently Asked Questions
How many marks does this question carry in CBSE Class 10 Science 2025?
This question carries 3 marks in the CBSE Class 10 Science 2025 examination.
Which chapter does this question come from in Science?
This question is from the chapter "Chemical Reactions and Equations" in the CBSE Class 10 Science syllabus.
What topic does this question cover in Science?
This question covers the topic "Chemical Reactions and Equations" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2025 paper?
This is a Short Answer question from Section C in the CBSE Class 10 Science 2025 paper.