Mayank Jain

 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}_...

 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...

 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 ...

 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...

 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 ...

 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 (...

  ✅ 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...

  ✅ What is Reduction? (Class 10 Science – Chapter: Chemical Reactions and Equations) 📘 Definition (CBSE Standard): Reduction is a chemical process in which a substance: Loses oxygen , or Gains hydrogen 🔁 Reduction Can Be Understood As: Type of Change Description Example Loss of Oxygen Substance gives up oxygen CuO + H 2 → Cu + H 2 O \text{CuO} + \text{H}_2 \rightarrow \text{Cu} + \text{H}_2\text{O} Gain of Hydrogen Substance gains hydrogen atoms Cl 2 + H 2 → 2 HCl \text{Cl}_2 + \text{H}_2 \rightarrow 2\text{HCl} 🧪 Example from NCERT (Activity 1.11): CuO + H 2 → Heat Cu + H 2 O \text{CuO} + \text{H}_2 \xrightarrow{\text{Heat}} \text{Cu} + \text{H}_2\text{O} Copper oxide (CuO) loses oxygen to become copper (Cu) ✅ So, CuO is reduced . 📌 Real-Life Examples of Reduction: Extraction of metals : Metal oxides are reduced to pure metals during extraction. Example: ZnO + C → Zn + CO \text{ZnO} + \text{C} \rightarrow \text{Zn} + \...

  ✅ What is Oxidation? (Class 10 Science – Chapter: Chemical Reactions and Equations) 📘 Definition (CBSE Standard): Oxidation is a chemical process in which a substance: Gains oxygen , or Loses hydrogen 🔁 Oxidation Can Be Understood As: Oxidation Type Description Example Gain of Oxygen Substance reacts with or gains oxygen C + O 2 → CO 2 \text{C} + \text{O}_2 \rightarrow \text{CO}_2 Loss of Hydrogen Substance loses hydrogen atoms H 2 S + Cl 2 → S + 2 HCl \text{H}_2\text{S} + \text{Cl}_2 \rightarrow \text{S} + 2\text{HCl} 🧪 Example from NCERT (Activity 1.11): 2 Cu + O 2 → Heat 2 CuO 2\text{Cu} + \text{O}_2 \xrightarrow{\text{Heat}} 2\text{CuO} Copper (Cu) gains oxygen and forms copper oxide (CuO) ✅ So, copper is oxidised . 📌 Real-Life Examples: Rusting of iron : Fe + O 2 + H 2 O → Fe 2 O 3 ⋅ x H 2 O \text{Fe} + \text{O}_2 + \text{H}_2\text{O} \rightarrow \text{Fe}_2\text{O}_3\cdot x\text{H}_2\text{O} Iron gets oxidised to f...

 Certainly, Mayank! Here's a CBSE Class 10–aligned explanation of Activity 1.11 , along with an answer to the Recall of Activity 1.1 . The focus is on conceptual clarity, oxidation-reduction (redox) concepts, and exam readiness. 🔥 Activity 1.11 – Oxidation and Reduction (Redox Reaction) (Class 10 Science – Chapter 1: Chemical Reactions and Equations) 🎯 Objective: To demonstrate how a metal (copper) undergoes oxidation and how the product can be reduced using hydrogen gas. 🧪 Materials Required: Copper powder (about 1 gram) China dish Heat source (burner or spirit lamp) Hydrogen gas (for part 2 of the reaction) 🔬 Procedure: Take a small quantity of copper powder in a china dish . Heat the copper gently. Observe any colour change. Now, pass hydrogen gas over the heated copper oxide . 👁️ Observations: Step What Happens Chemical Equation 1. Heating copper Surface turns black due to formation of copper(II) oxide (CuO) 2 Cu...

 Certainly, Mayank. Here's a clear, CBSE Class 10 Science–oriented explanation of Oxidation and Reduction Reactions , designed for student clarity, concept-building, and exam readiness. 🔥 Oxidation and Reduction Reactions (Class 10 Science – Chapter 1: Chemical Reactions and Equations) 📘 Definition of Oxidation: Oxidation is a chemical reaction in which a substance gains oxygen or loses hydrogen . 🔬 Examples of Oxidation: Magnesium burning in air: 2 Mg + O 2 → 2 MgO 2\text{Mg} + \text{O}_2 \rightarrow 2\text{MgO} (Magnesium gains oxygen → oxidation) Carbon burning to form carbon dioxide: C + O 2 → CO 2 \text{C} + \text{O}_2 \rightarrow \text{CO}_2 Removal of hydrogen: H 2 S + Cl 2 → 2 HCl + S \text{H}_2\text{S} + \text{Cl}_2 \rightarrow 2\text{HCl} + \text{S} (Hydrogen is removed from H₂S → oxidation) 📘 Definition of Reduction: Reduction is a chemical reaction in which a substance loses oxygen or gains hydrogen . 🔬 Examples of Reductio...

 Certainly, Mayank! Here's a CBSE Class 10–friendly explanation of the Neutralization Reaction , written in a clear, exam-ready manner for your students — with definitions, equations, and key points. ⚖️ Neutralization Reaction (Class 10 Science – Chapter 1: Chemical Reactions and Equations) 📘 Definition: A neutralization reaction is a chemical reaction in which an acid reacts with a base to form salt and water . ✅ The acid and base neutralize each other’s effect. 🔬 General Form: Acid + Base → Salt + Water \text{Acid} + \text{Base} \rightarrow \text{Salt} + \text{Water} 🧪 Example: NaOH ( a q ) + HCl ( a q ) → NaCl ( a q ) + H 2 O ( l ) \text{NaOH} (aq) + \text{HCl} (aq) \rightarrow \text{NaCl} (aq) + \text{H}_2\text{O} (l) Sodium hydroxide (NaOH) is a base Hydrochloric acid (HCl) is an acid They react to form sodium chloride (NaCl) and water (H₂O) 🔍 Explanation: H⁺ ions from the acid combine with OH⁻ ions from the base to form water. T...

 Certainly, Mayank! Here's a clear, CBSE-exam–oriented explanation of the Precipitation Reaction for Class 10 Science students, with definitions, examples, and concepts aligned with the NCERT syllabus. 🧪 Precipitation Reaction (Class 10 Science – Chapter 1: Chemical Reactions and Equations) 📘 Definition: A precipitation reaction is a type of chemical reaction in which two aqueous solutions react to form an insoluble solid called a precipitate . ✅ This precipitate appears as a solid that settles at the bottom of the reaction mixture. 🔬 General Form: A B ( a q ) + C D ( a q ) → A D ( s ) ↓ + C B ( a q ) AB (aq) + CD (aq) \rightarrow AD (s) ↓ + CB (aq) AB and CD are aqueous ionic compounds AD is the precipitate (solid) CB remains dissolved in water (aqueous) 🧪 Examples from NCERT / CBSE Class 10: ✅ 1. Barium Chloride + Sodium Sulphate (Activity 1.10) BaCl 2 ( a q ) + Na 2 SO 4 ( a q ) → BaSO 4 ( s ) ↓ + 2 NaCl ( a q ) \text{BaCl}_2 (aq) + \te...

 Certainly, Mayank! Here's a clear, CBSE Class 10–level explanation of Activity 1.10 , followed by answers to the Recall Activity 1.2 , all framed in a structured, exam-friendly and conceptually strong manner. 🧪 Activity 1.10 – Double Displacement & Precipitation Reaction (Chapter 1: Chemical Reactions and Equations – Class 10 Science) 🎯 Objective: To demonstrate the formation of a precipitate through a double displacement reaction . 🔬 Materials Required: Sodium sulphate solution (Na₂SO₄) Barium chloride solution (BaCl₂) 2 test tubes 🔍 Procedure: Take 3 mL of Na₂SO₄ solution in one test tube. Take 3 mL of BaCl₂ solution in another test tube. Mix the two solutions together. Observe the changes. 👁️ Observation: A white, insoluble solid is formed. This solid is a precipitate of barium sulphate (BaSO₄) . Sodium chloride (NaCl) remains dissolved in the solution. 🧪 Balanced Chemical Equation: Na 2 SO 4 ( a q ) + BaCl 2...

 Certainly, Mayank. Here's a clear, empathetic, and CBSE-exam–friendly explanation of the Double Displacement Reaction , designed for Class 10 Science students . It avoids humour and focuses on clarity , concept-building , and exam preparation . 🔄 Double Displacement Reaction (Chapter 1: Chemical Reactions and Equations – Class 10 Science) 📘 Definition: A double displacement reaction is a type of chemical reaction in which two compounds react by exchanging ions to form two new compounds . ✅ One of the new products is often a precipitate (insoluble solid) , gas , or water . 🧪 General Reaction Format: A B + C D → A D + C B AB + CD \rightarrow AD + CB A and C are cations (positive ions) B and D are anions (negative ions) The ions are exchanged between the compounds 📌 Key Characteristics: Feature Description Reactants Two ionic compounds in aqueous solution Process Exchange of ions between reactants Products Usually includes pr...

 Great! Let's explain Double Displacement Reaction in a way that's funny, visual, and easy to understand , especially for Class 10 CBSE students — with a relatable analogy and a solid scientific explanation. 🔁 Double Displacement Reaction – Made Funny & Easy (Chapter 1: Chemical Reactions and Equations – Class 10 Science) 🎯 Scientific Definition: A double displacement reaction is a reaction where two compounds exchange their ions to form two new compounds . A B + C D → A D + C B AB + CD \rightarrow AD + CB ✅ Ions of A and C swap partners! 🎭 Funny Analogy: "Dance Partner Switch!" 💃🕺 👫 Couple 1 = A 💖 B 👫 Couple 2 = C 💖 D 🎉 At the School Dance: Suddenly, there’s a partner swap! 🕺 A dances with D 🕺 C pairs up with B New couples are: A 💖 D C 💖 B Everyone’s happy… or confused 🤪 But that’s chemistry! 🧪 Real Chemistry Example: BaCl 2 ( a q ) + Na 2 SO 4 ( a q ) → BaSO 4 ( s ) + 2 NaCl ( a q ) \text{BaCl}_2 (aq) + \text{...