Chapter 3: Metals & Non-Metals is one of the most important chapters in MP Board Class 10 Science, carrying 8–12 marks in the annual board exam. This chapter covers the physical and chemical properties of metals and non-metals, the reactivity series, extraction of metals from ores (metallurgy), and corrosion — its causes, prevention, and economic impact. Questions range from 1-mark MCQs to 5-mark detailed explanations with balanced equations. Mastering this chapter is essential for both board exams and competitive foundation exams.

⚙️ Physical Properties — Metals vs Non-Metals

Metals and non-metals have distinctly different physical properties. Understanding these differences helps in classifying elements and predicting their behaviour in chemical reactions.

📊 Comparison Table: Metals vs Non-Metals

🔑 Key Physical Properties in Detail

1. Malleability

Malleability is the property of metals to be beaten into thin sheets. This is possible because metals have layers of atoms that can slide over one another without breaking the metallic bond.

• Gold (Au) is the most malleable metal — can be beaten into sheets as thin as 0.0001 mm (gold leaf).
• Aluminium (Al) is used to make aluminium foil for food packaging.
• Silver (Ag) and Copper (Cu) are also highly malleable.

2. Ductility

Ductility is the property of metals to be drawn into thin wires. This occurs because metal atoms can rearrange along the length of the wire without breaking.

• Gold (Au) is the most ductile metal — 1 gram of gold can be drawn into a wire up to 2 km long.
• Copper (Cu) is widely used for electrical wiring due to its high ductility and conductivity.
• Aluminium (Al) wires are used for power transmission lines.

3. Electrical Conductivity

Metals conduct electricity due to the presence of free (mobile) electrons in their crystal lattice. These electrons can move freely through the metal and carry electric current.

• Silver (Ag) is the best conductor of electricity, followed by Copper (Cu) and Gold (Au).
• Copper is most commonly used for electrical wiring due to its good conductivity and lower cost.
• Graphite (a non-metal) can conduct electricity due to delocalised electrons in its layered structure.

4. Thermal Conductivity

Metals are good conductors of heat because free electrons transfer thermal energy rapidly through the metal. Cooking utensils are made of metals (Cu, Al, steel) because they conduct heat efficiently.

🧪 Chemical Properties

The chemical properties of metals and non-metals determine how they react with common substances like oxygen, water, acids, and bases. These reactions are the basis for understanding the reactivity series and extraction methods.

🔥 Reaction with Oxygen (Formation of Oxides)

Metals react with oxygen to form metal oxides. Most metal oxides are basic in nature — they react with water to form bases, or with acids to form salt and water.

⚗️ Metals + Oxygen → Metal Oxide

Different metals react with oxygen at different rates:

• Sodium (Na) and Potassium (K) react so vigorously with oxygen that they catch fire spontaneously in air. They are stored under kerosene to prevent contact.
• Magnesium (Mg) burns with a brilliant white flame to form MgO (magnesium oxide).
• Aluminium (Al) forms a thin, protective layer of Al₂O₃ on its surface that prevents further corrosion.
• Iron (Fe) burns only when heated strongly. Iron filings burn more readily.
• Copper (Cu) does not burn but slowly forms a black coating of CuO on heating.
• Gold (Au) and Platinum (Pt) do not react with oxygen at all — they are the least reactive.

🧪 Nature of Metal Oxides

Most metal oxides are basic — they turn red litmus blue and react with acids to form salt and water:

Some metal oxides like Al₂O₃ and ZnO are amphoteric — they react with both acids and bases:

⚗️ Non-Metals + Oxygen → Non-Metal Oxide

Non-metal oxides are acidic in nature — they turn blue litmus red and react with bases to form salt and water:

💧 Reaction with Water

Metals react with water to produce metal hydroxide and hydrogen gas. The vigour of the reaction depends on the reactivity of the metal.

📋 Reactivity of Metals with Water

Non-metals generally do not react with water. However, some non-metals like carbon react with steam: C + H₂O → CO + H₂ (water gas reaction, only at high temperatures).

🧪 Reaction with Acids

Metals react with dilute acids (HCl, H₂SO₄) to produce salt and hydrogen gas.

🔑 Key Observations

• The vigour of the reaction depends on the reactivity of the metal.
• Highly reactive metals (Na, K) react explosively — these are NOT tested with acids in the lab for safety.
• Moderately reactive metals (Zn, Fe, Mg, Al) react readily with dilute acids.
• Less reactive metals (Cu, Ag, Au) do NOT react with dilute acids.
• The H₂ gas produced can be tested by the pop test — a burning matchstick near the gas produces a pop sound.
• Nitric acid (HNO₃) is NOT used because it is a strong oxidizing agent and produces oxides of nitrogen instead of H₂.

❌ Reaction of Non-Metals with Acids

Non-metals generally do NOT react with dilute acids to produce hydrogen gas. This is because non-metals cannot displace hydrogen from acids.

🧪 Reaction with Bases

Some metals react with strong bases (alkalis like NaOH, KOH) to produce hydrogen gas. This property is limited to amphoteric metals like Zn and Al.

Non-metals like silicon can also react with bases: Si + 2NaOH + H₂O → Na₂SiO₃ + 2H₂↑ (Sodium silicate).

📊 Chemical Properties Summary Table

📊 Reactivity Series of Metals

The reactivity series (also called the activity series) is a list of metals arranged in order of decreasing reactivity. The most reactive metal is at the top, and the least reactive is at the bottom. This series is fundamental to understanding displacement reactions, extraction methods, and corrosion.

🔺 Reactivity Series (Top to Bottom)

🔑 Reactivity Series — Mnemonic

⚡ Displacement Reactions Based on Reactivity

Displacement reaction: A more reactive metal displaces a less reactive metal from its salt solution. This principle is used in many applications and is a very common exam question.

Observation: When iron is placed in blue copper sulphate solution —

• The blue colour of CuSO₄ solution fades gradually.
• A reddish-brown coating of copper is deposited on the iron nail.
• This is because Fe is more reactive than Cu and displaces it.

🔬 The Reactivity Series — Why it Matters

• Displacement Reactions: Predict whether one metal can displace another from its salt solution.
• Extraction of Metals: Determines the method used to extract a metal from its ore.
• Corrosion: More reactive metals corrode more easily.
• Electrochemical Series: Basis for Galvanic cells and batteries.

⛏️ Extraction of Metals (Metallurgy)

Metallurgy is the process of extracting metals from their ores and refining them for use. The method of extraction depends on the position of the metal in the reactivity series.

🏭 Step-by-Step Process: Ore to Pure Metal

Step 1: Mining → Crushing → Concentration (Enrichment of Ore)

The ore obtained from the earth’s crust contains impurities like sand, clay, and rocks (called gangue). The ore must be concentrated to remove gangue before further processing.

• Gangue: The unwanted earthy impurities (sand, clay, rock particles) present in the ore.
• Concentration: The process of removing gangue from the ore to increase the percentage of metal in the ore.

Methods of Concentration

Step 2: Conversion of Concentrated Ore into Metal Oxide

The concentrated ore is converted into its oxide form, which is then reduced to the metal. This is done by either roasting (for sulphide ores) or calcination (for carbonate/hydroxide ores).

Step 3: Reduction of Metal Oxide to Metal

The metal oxide is reduced to the free metal. The method depends on the reactivity of the metal:

A. Reduction by Carbon (Smelting) — for moderately reactive metals

Metals like Zn, Fe, Pb, Sn are extracted by heating their oxides with carbon (coke). Carbon acts as a reducing agent, removing oxygen from the metal oxide.

Blast Furnace for Iron: Iron is extracted from haematite (Fe₂O₃) using carbon monoxide as the reducing agent. The blast furnace operates at ~1900°C and produces molten iron (pig iron).

B. Reduction by Electrolysis — for highly reactive metals

Metals that are highly reactive (K, Na, Ca, Mg, Al) cannot be reduced by carbon because they have a strong affinity for oxygen. They are extracted by electrolytic reduction — passing electricity through their molten (fused) compounds.

C. Reduction by Aluminium (Thermite Process) — for high melting metals

Aluminium is a strong reducing agent. It is used to reduce oxides of metals like Cr, Mn, Fe in the Thermite process.

The thermite reaction produces enormous heat (∼3000°C), enough to weld railway tracks and extract metals like chromium and manganese.

Step 4: Refining of Metals

The metal obtained after reduction is impure. It is refined to obtain high-purity metal. The most common method is electrolytic refining.

🔋 Electrolytic Refining

🔄 Complete Extraction Flowchart

📊 Extraction Method Based on Reactivity Series

🔧 Corrosion — Rusting, Tarnishing & Prevention

Corrosion is the gradual destruction of metals by chemical or electrochemical reaction with their environment. It is a natural process that converts refined metals into more stable compounds (oxides, hydroxides, sulphides).

🟤 Rusting of Iron

Conditions required for rusting: Iron rusts only when both oxygen (air) AND water are present.

🔬 Activity to Show Conditions for Rusting

Take three test tubes with iron nails:

• Test tube A: Nail + water (air excluded by oil layer) → No rust (air needed!)
• Test tube B: Nail + dry air (with anhydrous CaCl₂) → No rust (water needed!)
• Test tube C: Nail + both water and air → Rust forms!

⚪ Tarnishing of Other Metals

🛡️ Prevention of Corrosion

Corrosion causes massive economic losses. Several methods are used to prevent it:

1️⃣ Galvanization

• Zinc is more reactive than iron, so it corrodes preferentially (sacrificial protection).
• Even if the zinc coating is scratched, the zinc corrodes first, protecting the iron underneath.
• Used for: iron buckets, pipes, roofs, automobile parts.

2️⃣ Electroplating

Coating a metal with a thin layer of another metal (Cr, Ni, Cu, Ag, Au) using electrolysis.

• Chrome plating: Car bumpers, taps, kitchen appliances — shiny and rust-resistant.
• Silver/Gold plating: Decorative items, jewellery.
• Tin plating: Food cans (tin is non-toxic and corrosion-resistant).

3️⃣ Alloying

Mixing metals with other elements to form alloys that resist corrosion.

• Stainless steel: Fe + Cr + Ni — does not rust. Chromium forms a protective oxide layer.
• Brass: Cu + Zn — more corrosion-resistant than pure copper.
• Bronze: Cu + Sn — ancient alloy, highly durable.

4️⃣ Paint, Oil & Grease

Applying a protective layer that prevents contact with air and moisture.

• Paint: Used on iron gates, bridges, ships.
• Oil/Grease: Used on machine parts, tools.
• Plastic coating: Used on handles, garden furniture.

5️⃣ Sacrificial Protection

Attaching a more reactive metal (Mg, Zn) to the structure to be protected. The more reactive metal corrodes first, saving the structure.

• Used for: underground pipelines, ship hulls, water tanks.
• Magnesium blocks are attached to the hulls of ships to prevent corrosion of the steel hull.

📊 Corrosion Prevention Methods Summary

📝 Practice Questions (With Answers)

1. Q1: An element A reacts with oxygen to form compound B which has high melting point. This compound is soluble in water and turns red litmus blue. Identify element A and compound B. Write the balanced equation and state the nature of B.
2. Q2: Why is sodium metal stored under kerosene? What happens when a small piece of sodium is dropped into water? Write the balanced chemical equation.
3. Q3: Explain the extraction of iron from its ore. Describe the role of carbon monoxide in the blast furnace and write the chemical equation involved.
4. Q4: What is galvanization? Why is zinc used for galvanizing iron even though it is more reactive than iron? Explain the principle behind this method.
5. Q5: A metal M does not react with dilute HCl but reacts with oxygen to form a black compound. When this black compound is heated with hydrogen gas, it forms reddish-brown M again. Identify M and write all chemical equations.
6. Q6: Arrange the following metals in decreasing order of reactivity: Zn, Cu, Na, Fe, Ag, Al, Ca. Which of these metals would react with cold water? Which would not react with dilute HCl?

✅ Answer Key

• A1: A = Mg (Magnesium), B = MgO (Magnesium oxide).
  2Mg + O₂ → 2MgO. MgO is basic in nature — turns red litmus blue.
  MgO + H₂O → Mg(OH)₂ (magnesium hydroxide — a base).
• A2: Sodium is stored under kerosene to prevent contact with air (O₂) and moisture (H₂O) as it reacts explosively with both.
  2Na + 2H₂O → 2NaOH + H₂↑
  Sodium catches fire spontaneously on water — the reaction is highly exothermic.
• A3: Iron is extracted from haematite (Fe₂O₃) in a blast furnace using coke (C) and limestone (CaCO₃). Coke burns to form CO, which reduces Fe₂O₃ to Fe:
  Fe₂O₃ + 3CO → 2Fe + 3CO₂↑
  Limestone removes impurities as slag (CaSiO₃).
• A4: Galvanization is coating iron/steel with a layer of zinc. Zinc is more reactive than iron, so it corrodes preferentially (sacrificial protection). Even if scratched, zinc corrodes first, protecting the iron underneath. This works because Zn is above Fe in the reactivity series.
• A5: M = Cu (Copper).
  2Cu + O₂ → 2CuO (black copper oxide)
  CuO + H₂ → Cu + H₂O (hydrogen reduces CuO to reddish-brown Cu)
  Cu does not react with dilute HCl because it is below hydrogen in the reactivity series.
• A6: Na → Ca → Al → Zn → Fe → Cu → Ag (decreasing order).
  Na and Ca react with cold water. Ag and Cu do not react with dilute HCl.

📋 Previous Year Questions (2017–2026)

Chapter 2: Acids, Bases & Salts is a high-weightage chapter in MP Board Class 10 Science, contributing 10–12 marks in the annual board exam. This chapter covers the classification of substances as acidic or basic, the pH scale, indicators, reaction of acids and bases with metals, carbonates, and each other (neutralization), and the preparation and uses of important salts. Questions range from 1-mark MCQs to 5-mark comprehensive answers. Understanding the reaction patterns and salt preparation methods is essential for board success.

🧪 Properties of Acids vs Bases

Acids and bases are two fundamental categories of chemical substances with opposing properties. Understanding their differences is critical for predicting chemical reactions and their applications in daily life.

📊 Comparison Table: Acids vs Bases

🔬 Reaction of Acids with Metals

Acids react with active metals (like Zn, Fe, Mg, Al) to produce hydrogen gas and a salt.

• Zn + 2HCl → ZnCl₂ + H₂↑ (Zinc reacts with hydrochloric acid)
• Mg + H₂SO₄ → MgSO₄ + H₂↑ (Magnesium reacts with sulphuric acid)
• 2Al + 6HCl → 2AlCl₃ + 3H₂↑ (Aluminium reacts with hydrochloric acid)

⚗️ Reaction of Acids with Metal Carbonates & Bicarbonates

Acids react with carbonates and bicarbonates to produce carbon dioxide gas, water, and a salt.

• CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂↑ (Limestone reacts with HCl)
• NaHCO₃ + HCl → NaCl + H₂O + CO₂↑ (Baking soda reacts with HCl)
• Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂↑ (Washing soda reacts with HCl)

🤝 Neutralization Reaction (Acid + Base)

When an acid and a base react, they neutralize each other to form a salt and water. This is called a neutralization reaction.

• HCl + NaOH → NaCl + H₂O (Hydrochloric acid + Sodium hydroxide)
• H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O (Sulphuric acid + Sodium hydroxide)
• HCl + NH₄OH → NH₄Cl + H₂O (Hydrochloric acid + Ammonium hydroxide)

🧂 Reaction of Acids & Bases — Summary Flow

⚗️ Reaction of Base with Metals

Some bases (alkalis) react with certain reactive metals like Zn and Al to produce hydrogen gas.

• 2NaOH + Zn → Na₂ZnO₂ + H₂↑ (Sodium zincate is formed)
• 2NaOH + 2Al + 2H₂O → 2NaAlO₂ + 3H₂↑ (Sodium aluminate is formed)

📊 pH Scale with Examples

The pH scale (potential of Hydrogen) is a logarithmic scale used to specify the acidity or basicity of an aqueous solution. It ranges from 0 to 14, where 7 represents a neutral solution.

• pH < 7: Acidic solution — lower the pH, stronger the acid
• pH = 7: Neutral solution (pure water)
• pH > 7: Basic (alkaline) solution — higher the pH, stronger the base

🧪 pH Values of Common Substances

🔬 Importance of pH in Daily Life

• Human Body: Blood pH must remain around 7.35–7.45. Stomach pH (~1.5–3.5) helps digestion. pH imbalance can cause health issues.
• Plants: Most plants grow best at soil pH 6.5–7.5. Acidic soil is treated with lime (CaO).
• Digestion: Our stomach produces HCl for digestion. Excess causes acidity, treated with antacids (bases).
• Tooth Decay: Bacteria produce acids (pH < 5.5) that demineralize tooth enamel. Toothpaste (basic) neutralizes the acid.
• Bee Sting: Bee sting injects formic acid (acidic) — treated with baking soda (base).
• Wasp Sting: Wasp sting is alkaline — treated with vinegar (acid).

🎨 Indicators (Litmus, Phenolphthalein, Methyl Orange)

Indicators are substances that change colour in acidic or basic media. They help us determine whether a substance is acidic or basic without tasting or touching it.

🔵🔴 Types of Indicators

🧪 Natural Indicators

• Litmus: Extracted from lichens. Blue litmus turns red in acid; red litmus turns blue in base.
• Turmeric: Yellow in acid/neutral, turns red in base.
• Red Cabbage: Contains anthocyanin — red in acid, greenish-yellow in base.
• China Rose (Hibiscus): Dark magenta in acid, bright green in base.
• Methyl Orange: Synthetic indicator — red in acid, yellow in base.

📋 Indicator Colour Chart

🧪 pH Indicators — Universal Indicator

A universal indicator is a mixture of several indicators that gives a distinct colour for each pH value. By comparing the colour with a standard pH colour chart, the approximate pH of a solution can be determined.

• Red → Strongly acidic (pH 1–2)
• Orange/Yellow → Moderately acidic (pH 3–5)
• Green → Neutral (pH 7)
• Blue → Moderately basic (pH 8–10)
• Violet → Strongly basic (pH 11–14)

🧪 Olfactory Indicators

Substances whose smell changes in acidic or basic media are called olfactory indicators.

• Onion: Characteristic smell vanishes when treated with a base.
• Vanilla extract: Smell vanishes when treated with a base.

🧂 Common Salts — Preparation & Uses

A salt is an ionic compound formed by the neutralization reaction between an acid and a base. Salts consist of positive ions (cations) from the base and negative ions (anions) from the acid.

1️⃣ Sodium Chloride (NaCl) — Common Salt

Preparation

• Obtained by evaporation of seawater in salt pans
• Also mined from underground salt deposits (rock salt)
• Impure NaCl is dissolved in water, filtered, and recrystallized to get pure NaCl

Uses

• Essential seasoning in food (table salt)
• Preservation of fish, meat, and pickles
• Raw material for manufacturing Na₂CO₃, NaOH, Cl₂, HCl
• Used in the chlor-alkali process to manufacture NaOH and Cl₂

⚡ Chlor-Alkali Process

When electricity is passed through an aqueous solution of NaCl (brine), it decomposes to form NaOH, Cl₂, and H₂.

This is an important industrial process and is frequently asked in MP Board exams.

2️⃣ Sodium Bicarbonate (NaHCO₃) — Baking Soda

Preparation

Prepared by Solvay process. A cold and concentrated solution of sodium chloride is treated with ammonia and carbon dioxide:

• NaCl + NH₃ + CO₂ + H₂O → NaHCO₃ + NH₄Cl
• NaHCO₃ is sparingly soluble in water, so it precipitates out

Uses

• Used in baking powder (NaHCO₃ + tartaric acid) — produces CO₂ that makes cakes and bread fluffy
• Used as an antacid to neutralize excess stomach acid
• Used in fire extinguishers — produces CO₂ gas when heated
• Used in cleaning and as a mild disinfectant

🔥 Decomposition of Baking Soda

When heated, baking soda decomposes to produce CO₂:

3️⃣ Bleaching Powder (CaOCl₂) — Calcium Oxychloride

Preparation

Prepared by passing chlorine gas over dry slaked lime (Calcium hydroxide):

Conditions: Dry slaked lime, low temperature

Uses

• Used for bleaching cotton, linen, wood pulp in paper industry
• Used as a disinfectant for water purification and sanitation
• Used in the manufacture of chloroform (CHCl₃)
• Used for bleaching in textile and laundry industries

4️⃣ Gypsum (CaSO₄·2H₂O) — Calcium Sulphate Dihydrate

Preparation of Plaster of Paris

Plaster of Paris (CaSO₄·½H₂O) is a white powder that sets into a hard mass when mixed with water.

Uses of Gypsum

• Used in the manufacture of cement (retards setting time)
• Used as a fertilizer (source of calcium and sulphur)
• Used in making chalk and blackboard
• Used in plastering walls and ceilings

Uses of Plaster of Paris

• Making statues, toys, and decorative items
• Used in orthopaedics for setting fractured bones
• Used in construction for false ceilings and decorative mouldings

5️⃣ Sodium Carbonate (Na₂CO₃·10H₂O) — Washing Soda

Preparation

Prepared by heating baking soda (NaHCO₃), followed by recrystallization:

• Step 1: 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂↑ (heating)
• Step 2: Na₂CO₃ + 10H₂O → Na₂CO₃·10H₂O (recrystallization from water)

Uses

• Used as a cleaning agent (washing soda) for laundry
• Used in the manufacture of glass, soap, and paper
• Used for removing permanent hardness of water
• Used in the Solvay process for manufacturing NaHCO₃

📊 Summary Table: Common Salts

📝 Practice Questions (With Answers)

1. Q1: What happens when a piece of zinc metal is dropped into dilute hydrochloric acid? Write the balanced chemical equation and name the gas evolved.
2. Q2: Two solutions A and B have pH values of 3 and 11 respectively. Which of these is acidic and which is basic? Calculate the hydrogen ion concentration of each.
3. Q3: Explain the preparation of bleaching powder with a balanced chemical equation. Write any two uses of bleaching powder.
4. Q4: What is the difference between baking soda (NaHCO₃) and washing soda (Na₂CO₃·10H₂O)? How can baking soda be converted into washing soda?
5. Q5: Why does blue litmus turn red when dipped in vinegar? Explain using the concept of acids and indicators.

✅ Answer Key

• A1: Zinc reacts with HCl to produce zinc chloride and hydrogen gas.
  Zn + 2HCl → ZnCl₂ + H₂↑
  Gas: Hydrogen (H₂). It burns with a pop sound near a flame.
• A2: Solution A (pH 3) is acidic. Solution B (pH 11) is basic.
  [H⁺] for A = 10⁻³ M, [H⁺] for B = 10⁻¹¹ M.
• A3: Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O. Uses: (i) Bleaching cotton and linen, (ii) Disinfecting drinking water.
• A4: NaHCO₃ is baking soda (mild base, used in food). Na₂CO₃·10H₂O is washing soda (strong base, used for cleaning).
  Conversion: 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂↑ (heating), followed by Na₂CO₃ + 10H₂O → Na₂CO₃·10H₂O.
• A5: Vinegar contains acetic acid (CH₃COOH). Acids release H⁺ ions in solution which react with the colouring agent in blue litmus, turning it red.

📋 Previous Year Questions (2017–2026)

Chapter 1: Chemical Reactions & Equations is a fundamental chapter in MP Board Class 10 Science, carrying 8–10 marks in the annual board exam. This chapter introduces the concept of chemical changes, types of chemical reactions, balancing chemical equations, and oxidation-reduction processes. Questions range from 1-mark MCQs and VSA to 3-mark short answer and 5-mark long answer questions. Mastery of writing and balancing chemical equations is essential for scoring high marks in this chapter.

⚗️ Chemical Equations & Balancing

A chemical equation is a symbolic representation of a chemical reaction using chemical formulas. Reactants are written on the left side and products on the right side, separated by an arrow (→).

📝 Rules for Writing Chemical Equations

• Write the correct chemical formulas of reactants and products
• Use the arrow (→) to separate reactants from products
• Indicate physical states: (s) solid, (l) liquid, (g) gas, (aq) aqueous
• Balance the equation so that the number of atoms of each element is equal on both sides
• Use coefficients (numbers before formulas) to balance — never change subscripts

📐 Solved Example 1: Burning of Magnesium

Unbalanced: Mg + O₂ → MgO

Step 1: Count atoms — Left: Mg=1, O=2 | Right: Mg=1, O=1

Step 2: Balance oxygen — put coefficient 2 before MgO: Mg + O₂ → 2MgO

Step 3: Balance magnesium — put coefficient 2 before Mg: 2Mg + O₂ → 2MgO

Balanced: 2Mg + O₂ → 2MgO

📐 Solved Example 2: Decomposition of Ferrous Sulphate

Unbalanced: FeSO₄ → Fe₂O₃ + SO₂ + SO₃

Step 1: Count atoms — Left: Fe=1, S=1, O=4 | Right: Fe=2, S=2, O=8

Step 2: Balance Fe — put coefficient 2 before FeSO₄: 2FeSO₄ → Fe₂O₃ + SO₂ + SO₃

Step 3: Balance S — Left S=2, Right S=2 ✓ | Balance O — Left O=8, Right O=8 ✓

Balanced: 2FeSO₄ → Fe₂O₃ + SO₂ + SO₃

📐 Solved Example 3: Reaction of Lead Nitrate with Potassium Iodide

Unbalanced: Pb(NO₃)₂ + KI → PbI₂ + KNO₃

Step 1: Count atoms — Left: Pb=1, N=2, O=6, K=1, I=1 | Right: Pb=1, I=2, K=1, N=1, O=3

Step 2: Balance I — put coefficient 2 before KI: Pb(NO₃)₂ + 2KI → PbI₂ + KNO₃

Step 3: Balance NO₃ — Left NO₃=2, put coefficient 2 before KNO₃: Pb(NO₃)₂ + 2KI → PbI₂ + 2KNO₃

Step 4: Verify — Left: Pb=1, N=2, O=6, K=2, I=2 | Right: Pb=1, I=2, K=2, N=2, O=6 ✓

Balanced: Pb(NO₃)₂ + 2KI → PbI₂ + 2KNO₃

➕ Combination Reactions

A combination reaction is a reaction in which two or more substances (elements or compounds) combine to form a single new substance. The general form is: A + B → AB.

🔥 Examples of Combination Reactions

• Burning of coal: C + O₂ → CO₂ (Carbon + Oxygen → Carbon dioxide)
• Formation of water: 2H₂ + O₂ → 2H₂O (Hydrogen + Oxygen → Water)
• Formation of calcium oxide: 2Ca + O₂ → 2CaO (Calcium + Oxygen → Calcium oxide)
• Burning of magnesium: 2Mg + O₂ → 2MgO (Magnesium + Oxygen → Magnesium oxide — bright white flame)

🧪 Decomposition Reactions

A decomposition reaction is a reaction in which a single compound breaks down into two or more simpler substances. The general form is: AB → A + B. Decomposition reactions are the opposite of combination reactions.

🔬 Types of Decomposition Reactions

🔄 Displacement Reactions

A displacement reaction is a reaction in which a more reactive element displaces a less reactive element from its compound. The general form is: A + BX → AX + B (where A is more reactive than B).

⚔️ Examples of Displacement Reactions

• Iron + Copper Sulphate: Fe + CuSO₄ → FeSO₄ + Cu (Iron displaces copper — blue solution turns green)
• Zinc + Copper Sulphate: Zn + CuSO₄ → ZnSO₄ + Cu (Zinc displaces copper — blue colour fades)
• Lead + Copper Chloride: Pb + CuCl₂ → PbCl₂ + Cu (Lead displaces copper)

🔄 Double Displacement Reactions

A double displacement reaction is a reaction in which two compounds exchange their ions (or radicals) to form two new compounds. The general form is: AB + CD → AD + CB.

Double displacement reactions are further classified into precipitation reactions (where an insoluble solid forms) and neutralization reactions (where an acid and base react to form salt and water).

🧪 Examples of Double Displacement Reactions

• Precipitation (Yellow Precipitate): Pb(NO₃)₂ + 2KI → PbI₂ + 2KNO₃ (Yellow precipitate of PbI₂ forms)
• Precipitation (White Precipitate): NaCl + AgNO₃ → AgCl + NaNO₃ (White precipitate of AgCl forms)
• Neutralization: HCl + NaOH → NaCl + H₂O (Acid + Base → Salt + Water)

⚡ Oxidation & Reduction

📖 Definitions

• Oxidation: Addition of oxygen OR removal of hydrogen from a substance
• Reduction: Addition of hydrogen OR removal of oxygen from a substance
• Redox Reaction: A reaction where oxidation and reduction occur simultaneously
• Oxidizing Agent: A substance that provides oxygen (or removes hydrogen) — gets reduced itself
• Reducing Agent: A substance that provides hydrogen (or removes oxygen) — gets oxidized itself

📊 Common Examples of Redox Reactions

🦀 Corrosion — A Real-World Example of Oxidation

Corrosion is the slow destruction of metals due to reaction with oxygen, moisture, and other substances in the environment. The most well-known example is rusting of iron:

4Fe + 3O₂ + 2xH₂O → 2Fe₂O₃·xH₂O (Hydrated iron oxide — rust)

• Rusting requires both oxygen and water
• Prevention: Painting, oiling, galvanization (coating with zinc), alloying
• Silver tarnishes (turns black) due to reaction with H₂S in air: 4Ag + 2H₂S + O₂ → 2Ag₂S + 2H₂O

🍏 Rancidity — Oxidation of Food

Rancidity is the spoilage of food containing fats and oils due to oxidation, producing unpleasant smell and taste. Prevention methods include:

• Adding antioxidants (e.g., BHA, BHT) to packaged foods
• Storing food in airtight containers
• Refrigeration to slow down oxidation
• Packing in oxygen-free environment (nitrogen flushing)

📝 Practice Questions

1. Q1: Balance the following chemical equation: Fe + H₂O → Fe₃O₄ + H₂. Identify the type of reaction.
2. Q2: What happens when green ferrous sulphate crystals are heated? Write the balanced chemical equation and state the type of reaction.
3. Q3: Distinguish between displacement and double displacement reactions with one example each.
4. Q4: In the reaction ZnO + C → Zn + CO, identify the substance that is oxidized, reduced, the oxidizing agent, and the reducing agent.
5. Q5: Why do we apply paint on iron articles? Explain two methods to prevent rusting.

✅ Answer Key

• A1: 3Fe + 4H₂O → Fe₃O₄ + 4H₂. This is a displacement reaction (iron displaces hydrogen from water).
• A2: Green FeSO₄ crystals first lose water (turn white), then decompose: 2FeSO₄ → Fe₂O₃ + SO₂ + SO₃. This is a thermal decomposition reaction.
• A3: Displacement: Fe + CuSO₄ → FeSO₄ + Cu (one element + one compound). Double displacement: Pb(NO₃)₂ + 2KI → PbI₂ + 2KNO₃ (two compounds exchange ions).
• A4: Oxidized: C (Carbon gains oxygen). Reduced: ZnO (Zinc oxide loses oxygen). Reducing agent: C. Oxidizing agent: ZnO.
• A5: Paint prevents iron from coming into contact with oxygen and moisture, thus preventing rusting. Methods: (a) Galvanization — coating with zinc, (b) Oiling/greasing — creating a protective layer, (c) Alloying — making stainless steel.

📋 Previous Year Questions (2017–2026)

MP Board Previous Year Papers 2027 — Class 10 & 12 All Subjects (2017-2026)

MP Board ke Previous Year Papers (PYPs) solve karna exam mein 90%+ score ka सबसे बड़ा रहस्य है. Is page par aapko milega Class 10 aur Class 12 ke saare subjects ke 10 saal ke solved papers (2017-2026) with answers.

PYP Solve Karne ke 5 Fayde

1. Exam pattern pata chal jata hai — kaunse chapter se kitne marks ke questions aate hain
2. Time management seekho — actual exam mein time kaise lagana hai
3. Repeated questions identify karo — har saal kuch questions repeat hote hain
4. Confidence badhta hai — jaan pehchan pattern dekh kar dar kam hota hai
5. Weak areas pata chalte hain — jahan marks nahi aa rahe wahan zyada focus karo

PYQ Practice Tips

20-Year Rule: Pichle 10 saal ke papers 2 baar solve karo — ek baar chapter ke baad, doosri baar pre-board time. MP Board mein 60% questions previous years se repeat ya similar aate hain.

Smart Study Tips for MP Board 2027 — Learn Faster, Score Better

Smart Study ka matlab nahi hai kam padhna — smart study ka matlab hai efficient padhna. Is article mein hum discuss karenge science-backed smart study techniques jo MP Board Class 10 aur Class 12 students ko 90%+ score dila sakti hain.

1. Pomodoro Technique

25 minutes study, 5 minutes break. Har 4 cycles ke baad 15-20 min break. Isse aapki concentration 40% improve hoti hai. MP Board students ke liye yeh sabse effective technique hai.

2. Active Recall — सबसे Powerful Method

Chapter padhne ke baad turant ushe yaad karne ki koshish karo — book dekhe bina. Research kehta hai ki Active Recall normal reading se 50% zyada effective hai.

3. Smart Study Time Table

MP Board 2027 mein smart study karo — 95%+ score possible hai!

MP Board Previous Year Papers 2027 — Class 10 & 12 All Subjects (2017-2026)

MP Board ke Previous Year Papers (PYPs) solve karna exam mein 90%+ score ka सबसे बड़ा रहस्य है. Is page par aapko milega Class 10 aur Class 12 ke saare subjects ke 10 saal ke solved papers (2017-2026) with answers.

PYP Solve Karne ke 5 Fayde

1. Exam pattern pata chal jata hai — kaunse chapter se kitne marks ke questions aate hain
2. Time management seekho — actual exam mein time kaise lagana hai
3. Repeated questions identify karo — har saal kuch questions repeat hote hain
4. Confidence badhta hai — jaan pehchan pattern dekh kar dar kam hota hai
5. Weak areas pata chalte hain — jahan marks nahi aa rahe wahan zyada focus karo

PYQ Practice Tips

20-Year Rule: Pichle 10 saal ke papers 2 baar solve karo — ek baar chapter ke baad, doosri baar pre-board time. MP Board mein 60% questions previous years se repeat ya similar aate hain.

Smart Study Tips for MP Board 2027 — Learn Faster, Score Better

Smart Study ka matlab nahi hai kam padhna — smart study ka matlab hai efficient padhna. Is article mein hum discuss karenge science-backed smart study techniques jo MP Board Class 10 aur Class 12 students ko 90%+ score dila sakti hain.

1. Pomodoro Technique

25 minutes study, 5 minutes break. Har 4 cycles ke baad 15-20 min break. Isse aapki concentration 40% improve hoti hai. MP Board students ke liye yeh sabse effective technique hai.

2. Active Recall — सबसे Powerful Method

Chapter padhne ke baad turant ushe yaad karne ki koshish karo — book dekhe bina. Research kehta hai ki Active Recall normal reading se 50% zyada effective hai.

3. Smart Study Time Table

MP Board 2027 mein smart study karo — 95%+ score possible hai!

Table of Contents

1. Paper Overview and Exam Pattern
2. Section A – Objective Questions (1 Mark Each)
3. Section B – Very Short Answer Questions (2 Marks Each)
4. Section C – Short Answer Questions (3 Marks Each)
5. Section D – Long Answer Questions (5 Marks Each)
6. Download PDF and Tips

Key Takeaways

• The 2024 paper was balanced across all four sections
• Chemistry (30%), Physics (35%), and Biology (35%) had equal weightage
• NCERT-based questions comprised around 85% of the total paper
• Numerical and diagram-based questions are scoring if practiced well