Chemical Reactions and Equations Class 10: Extra Questions with Answers
In this comprehensive resource, you’ll find essential extra questions and answers related to CBSE Class 10 Science Chapter 1: Chemical Reactions and Equations. Whether you’re preparing for exams or simply want to reinforce your understanding, these practice questions cover crucial concepts.
Key Features:
- Practice Questions: Dive into a curated set of additional questions that align with the CBSE syllabus. These questions span various difficulty levels, ensuring thorough preparation.
- Answers and Solutions: Detailed solutions accompany each question, helping you grasp the underlying principles and mechanisms of chemical reactions.
- NCERT Aligned: Our content adheres to the latest NCERT textbook, ensuring accuracy and relevance.
Extra Questions
- What do you mean by chemical reactions. Give examples.Ans. A reaction in which a new substance is formed from original substances is called a chemical reaction. For example: rusting of iron, digestion of food etc.
- What are the four observations that are characteristic of a chemical reaction. List with examples.Ans The four observations that are characteristics of a chemical reaction are:
- a) Change in state
- b) Change in colour
- c) Change in temperature
- d) Evolution of gas
Burning Magnesium ribbon in air results in formation of magnesium oxide with dazzling white flame-this is an example where both change in state and change in temperature is seen.
Reaction of aq solution of lead nitrate with potassium iodide involves change in state as well as change in colour as yellow-coloured precipitates of lead iodide are formed.
Reaction of zinc granules with dil. HCl results in evolution of gas (Hydrogen) release of heat and also change in state.
- Why do we need to balance a chemical equation?Ans A chemical equation needs to be balanced in order to satisfy the law of conservation of mass that states that mass can neither be created nor destroyed in a chemical reaction.
- What is an unbalanced chemical equation known asAns. Skeletal equation
- Name two salts that are used in black and white photography.Ans. Silver bromide (AgBr) and silver iodide (AgI) are commonly used in black and white photography.
- What product is formed when quicklime (calcium oxide) reacts with water?Ans. Quicklime (CaO) reacts with water to form slaked lime (calcium hydroxide, Ca(OH)₂).
- Write the chemical formula for marble.Ans. The chemical formula for marble is CaCO₃ (calcium carbonate).
- Which type of reaction produces insoluble salts?Ans. Double displacement reactions often produce insoluble salts.
- Why is the combustion of Liquified Petroleum Gas (LPG) considered a chemical change?Ans. LPG combustion results in the formation of a new substance that cannot revert to its original state.
- What is the balanced equation for the reaction of potassium chlorate (KClO₃) on heating?Ans. 2KClO₃ (s) → 2KCl (s) + 3O₂ (g)
- Why is hydrogen peroxide stored in colored bottles?Ans. Colored bottles protect hydrogen peroxide from light, preventing its decomposition.
- Identify ‘x’, ‘y’, and ‘z’ in the following reaction:(a) x = gas; y = reaction condition; z = gas
(b) x = solid; y = liquid; z = gas
(c) x = number of moles of KClO₃; y = reaction condition; z = number of molecules of oxygen
(d) x = physical state of KClO₃ and KCl; y = reaction condition; z = physical state of O₂
Ans. The balanced chemical equation for the action of steam on iron is: [3Fe + 4H₂O → Fe₃O₄ + 4H₂] - Assertion (A): The balanced chemical equation for the action of steam on iron is: 3Fe + 4H₂O → Fe₃O₄ + 4H₂.
Reason ®: The law of conservation of mass holds good for a chemical equation.Answer: Both (A) and ® are true, and reason ® is the correct explanation of the assertion (A) - State the law followed by balancing a chemical equation.Answer: The law of conservation of mass states that mass can neither be created nor destroyed in a chemical reaction. The total mass of elements in the products must be equal to the total mass of elements in the reactants in a balanced equation.
Balanced Chemical Equation: 2Na (s) + 2H₂O (l) → 2NaOH (aq) + H₂ (g) - Explain the significance of photosynthesis.Ans. Photosynthesis is the process by which plants utilize carbon dioxide and water in the presence of sunlight to produce glucose and oxygen. It sustains life for all living beings.
Balanced Chemical Equation for Photosynthesis: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ - Write balanced chemical equations for the following reactions:(a) Hydrogen + Chlorine → Hydrogen chloride
Ans. H₂ (g) + Cl₂ (g) → 2HCl (g)
(b) Lead + Copper chloride → Lead chloride + Copper
Ans. Pb (s) + CuCl₂ (aq) → PbCl₂ (aq) + Cu (s)
(c) Zinc oxide + Carbon → Zinc + Carbon monoxide
Ans. ZnO (s) + C (s) → Zn (s) + CO (g). - Classify the reaction: Calcium oxide reacts vigorously with water to produce slaked lime.Ans. This reaction is a combination reaction.
