Get here CBSE Class 10 Science Extra Questions and Answers for Chapter 1 - Chemical Reactions and Equations. All these questions and answers are based on the NCERT textbook and are important for the preparations of the upcoming board exam. These extra questions will be helpful to revise the important topics and concepts. You can easily download all the questions and answers in PDF format.
CBSE Class 10 Science Extra Questions and Answers for Chapter 1 - Chemical Reactions and Equations:
1. Why do we need to balance a chemical equation?
We need to balance a chemical equation to satisfy the law of conservation of mass.
2. Name two salts that are used in black and white photography.
Two salts that are used in black and white photography are:
(i) Silver chloride
(ii) Silver bromide
3. What is the product formed on adding quick lime to water?
When quick lime (CaO) is added to water, the product formed is slaked lime Ca(OH)2 .
4. Write the chemical formula for marble.
Chemical formula for marble is CaCO3.
5. Which type of reaction produces insoluble salts?
Precipitation reaction produces insoluble salts.
6. A silver article turns black when kept in the open for a few days. Give reason for this change.
Because H2S gas present in the air reacts with silver forming a coating of black silver sulphide (Ag2S).
7. Name the phenomenon involved in turning of silver into silver sulphide in the above question.
The phenomenon involved in turning of silver into silver sulphide is called corrosion.
8. How does food become rancid?
Food becomes rancid when fat and oils present in the food are oxidised.
9. Why is respiration considered as an exothermic reaction?
Because heat is evolved during respiration.
10. Which gas is filled in the chips packets to prevent rancidity and why?
Nitrogen gas is filled in the chips packets.
Nitrogen being an inert gas prevents the oxidation of oils present in chips.
You may also download all the questions and answers in PDF from the link mentioned below:
While making the exam preparations, students should go through the Revised CBSE Syllabus for Class 10 Science so that they can avoid the deleted topics and prepare according to the topics that are prescribed by the board.