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class 10 science NCERT Solutions

 Here is a comprehensive, exam-oriented answer key for the NCERT Class 10 Science – Chapter 1: Chemical Reactions and Equations – Exercise Questions 1 to 20 , explained clearly and concisely for both teaching and revision : 1. Identify incorrect statements: Reaction: 2 PbO ( s ) + C ( s ) → 2 Pb ( s ) + CO 2 ( g ) 2\text{PbO}(s) + \text{C}(s) \rightarrow 2\text{Pb}(s) + \text{CO}_2(g) ✅ Correct analysis: Lead oxide (PbO) is reduced to lead. Carbon (C) is oxidised to CO₂. CO₂ is not getting oxidised , it is a product. ✅ Incorrect statements: (a) and (b) Answer: (i) (a) and (b) 2. Type of reaction: Fe 2 O 3 + 2 Al → Al 2 O 3 + 2 Fe \text{Fe}_2\text{O}_3 + 2\text{Al} \rightarrow \text{Al}_2\text{O}_3 + 2\text{Fe} ✅ Explanation: Aluminium displaces iron from its oxide → Displacement reaction Answer: (d) displacement reaction 3. Reaction of HCl with iron filings: Fe + 2 HCl → FeCl 2 + H 2 ↑ \text{Fe} + 2\text{HCl} \rightarrow \text{FeCl}_2 + \text{H}_...
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🧪 Corrosion

 Certainly, Mayank. Here's a clear, CBSE Class 10–level explanation of Corrosion , suitable for teaching, revision, and exam preparation. 🧪 Corrosion (Class 10 Science – Chapter 1 : Chemical Reactions and Equations – Section 1.3.1) 📘 Definition: Corrosion is the gradual destruction of metals due to the chemical reaction with substances in the environment, such as moisture, air, water, and acids . 🔍 Common Examples of Corrosion: Metal Corroded Form Appearance Iron Iron oxide (rust) Reddish-brown coating Copper Basic copper carbonate Green coating Silver Silver sulphide Black coating (tarnishing) 🧪 Rusting of Iron – A Type of Corrosion: 4 Fe + 3 O 2 + x H 2 O → 2 Fe 2 O 3 ⋅ x H 2 O 4\text{Fe} + 3\text{O}_2 + x\text{H}_2\text{O} \rightarrow 2\text{Fe}_2\text{O}_3 \cdot x\text{H}_2\text{O} (Rust is hydrated iron(III) oxide) ⚠️ Why is Corrosion Harmful? Weakens metal objects Damages bridges, buildings, pipelines, vehicles Causes...
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🧪 Rancidity

 Certainly, Mayank. Here's a concise, CBSE Class 10–level explanation of Rancidity , written in a way that is exam-friendly , easily teachable , and suitable for both classroom and online instruction. 🧪 Rancidity (Class 10 Science – Chapter: Chemical Reactions and Equations – Section 1.3.2) 📘 Definition: Rancidity is the process in which fats and oils get oxidised , resulting in a bad smell and unpleasant taste in food. 🔍 Cause of Rancidity: Rancidity occurs due to the oxidation of fats and oils when they are exposed to oxygen, light, or moisture over time. 🧠 Examples: Spoiled ghee or butter giving a bad odour Chips or snacks that taste bitter or stale Old cooking oil left uncovered or used repeatedly ⚠️ Why is Rancidity a Problem? Makes food unfit for consumption Reduces nutritional value Leads to food waste 🛡️ Methods to Prevent Rancidity: Method How it helps Use of antioxidants Chemicals like BHA and BHT slow ...
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Corrosion and Rancidity

 Certainly, Mayank. Here's a well-organized and CBSE Class 10–level explanation of Sections 1.3.1 (Corrosion) and 1.3.2 (Rancidity) , written to be exam-ready , easily teachable , and suitable for digital or classroom use. 📘 1.3.1 Corrosion (Class 10 Science – Chapter: Chemical Reactions and Equations) ✅ What is Corrosion? Corrosion is the slow wearing away of a metal due to the action of moisture, air, acids , and other environmental substances on its surface. 🔍 Examples of Corrosion: Metal Observation Iron Forms a reddish-brown flaky coating (rust) Copper Forms a green coating of copper carbonate Silver Develops a black coating of silver sulphide 🧪 Chemical Reaction of Rusting: 4 Fe + 3 O 2 + x H 2 O → 2 Fe 2 O 3 ⋅ x H 2 O 4\text{Fe} + 3\text{O}_2 + x\text{H}_2\text{O} \rightarrow 2\text{Fe}_2\text{O}_3 \cdot x\text{H}_2\text{O} (Rust: Hydrated iron(III) oxide) ⚠️ Why is Corrosion Harmful? Weakens metal structures like bridges, b...
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the Effects of Oxidation Reactions in Everyday Life?

 Certainly, Mayank. Here's a CBSE Class 10–level explanation of Section 1.3: "Have You Observed the Effects of Oxidation Reactions in Everyday Life?" , written in a clear, structured, and exam-oriented way for easy classroom presentation and student understanding. 📘 1.3 – Have You Observed the Effects of Oxidation Reactions in Everyday Life? (Chapter 1: Chemical Reactions and Equations – Class 10 Science) 🔍 Understanding the Concept: Oxidation reactions are not limited to laboratories—they also occur in many natural and everyday processes around us. These reactions often lead to visible and sometimes damaging effects , especially when substances react with oxygen in the air . 🌍 Common Effects of Oxidation in Daily Life: ✅ 1. Rusting of Iron Reaction: 4 Fe + 3 O 2 + x H 2 O → 2 Fe 2 O 3 ⋅ x H 2 O 4\text{Fe} + 3\text{O}_2 + x\text{H}_2\text{O} \rightarrow 2\text{Fe}_2\text{O}_3 \cdot x\text{H}_2\text{O} Occurs when iron reacts with oxygen and moisture ...
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question answer 3

 Certainly, Mayank. Here's a well-structured, CBSE-exam–oriented answer for all three questions, suitable for Class 10 Science students: Q1. Why does the colour of copper sulphate solution change when an iron nail is dipped in it? ✅ Answer: When an iron nail is dipped in copper sulphate (CuSO₄) solution , a displacement reaction occurs. Iron is more reactive than copper and displaces copper from its solution: Fe ( s ) + CuSO 4 ( a q ) → FeSO 4 ( a q ) + Cu ( s ) \text{Fe} (s) + \text{CuSO}_4 (aq) \rightarrow \text{FeSO}_4 (aq) + \text{Cu} (s) The blue colour of the copper sulphate solution fades as iron sulphate (FeSO₄) is formed (which is pale green in colour). A reddish-brown deposit of copper forms on the iron nail. Q2. Give an example of a double displacement reaction other than the one in Activity 1.10. ✅ Answer: Reaction between lead(II) nitrate and potassium iodide: Pb(NO 3 ) 2 ( a q ) + 2 KI ( a q ) → PbI 2 ( s ) + 2 KNO 3 ( a q ) \text{Pb(NO}_3)_2 (...
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redox

  ✅ What is a Redox Reaction? (Class 10 Science – Chapter: Chemical Reactions and Equations) 📘 Definition (CBSE Standard): A Redox Reaction is a chemical reaction in which oxidation and reduction take place simultaneously . One substance is oxidised (gains oxygen or loses hydrogen) Another substance is reduced (loses oxygen or gains hydrogen) 🔁 Breakdown of the Term “Redox”: Part Meaning Red Reduction – Loss of oxygen / gain of hydrogen Ox Oxidation – Gain of oxygen / loss of hydrogen 🧪 Example of a Redox Reaction (from NCERT): CuO + H 2 → Heat Cu + H 2 O \text{CuO} + \text{H}_2 \xrightarrow{\text{Heat}} \text{Cu} + \text{H}_2\text{O} Substance Process Reason CuO Reduction Loses oxygen to form Cu H₂ Oxidation Gains oxygen to form H₂O ✅ Since both oxidation and reduction occur in the same reaction → it is a Redox Reaction . 📌 More Examples: 1. Zinc and Copper Sulphate Reaction: Zn + CuSO 4 → ZnSO 4 + Cu \text{Zn...
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