The World of Metals and Non-metals

The Hook (The Mystery & Discovery)

A. Did you know that when Yashwant and Anandi visited a local ironsmith named Sudarshan uncle in a village in Rajasthan, they discovered that everyday tools like flat pans (tawas), buckets (baltis), tongs (chimtas), spades (phawras), axes (kulhadis), trowels (khurpis), and rakes (jelees) are forged by hammering red-hot iron metal heated over coal furnaces?

B. Imagine if you took a tiny 1-gram piece of gold—it is so extraordinarily ductile that you could pull and stretch it into a continuous wire spanning 2 kilometres in length!

C. Did you know that ancient Harappan artisans were master craftspersons who used copper and gold to craft intricate utensils and jewellery, yet they hardly ever used iron? It was only centuries later that the widespread adoption of iron tools, such as sturdy iron ploughs, revolutionized Indian agriculture and accelerated the progress of Indian civilization.

D. Imagine standing before a colossal monument that has defied the elements for over 1,600 years: the famous Iron Pillar of Delhi, erected during the reign of Chandragupta II. Standing at a height of 8 metres and weighing over 6,000 kilograms, this iron wonder has faced centuries of rain, wind, and harsh weather without developing any significant rust, showcasing the astonishing ancient Indian mastery over metallurgy and corrosion resistance.

E. Did you know that sodium metal is so soft that it can be effortlessly sliced with a simple butter knife, yet it is so fiercely reactive that it catches fire and explodes upon contact with air or water, forcing scientists to store it completely submerged in kerosene? Conversely, its non-metallic neighbor phosphorus spontaneous bursts into flame in atmospheric air, requiring it to be stored safely underwater.

F. Imagine burning a piece of magnesium metal ribbon—it combusts with a blinding, dazzling white flame, forming a fine white powder of magnesium oxide that dissolves in warm water to turn red litmus paper blue, proving that metal oxides are basic in nature! Meanwhile, burning sulfur powder in a deflagrating spoon releases sulfur dioxide gas, which dissolves in water to form sulfurous acid, turning blue litmus paper red and revealing that non-metal oxides are acidic.

Real-World Lesson (Why This Matters)

The study of metals and non-metals is not merely classroom chemistry; it forms the structural, technological, and biological bedrock of modern global society.

Structural Infrastructure and Transportation: Metals like iron and its alloy steel (a combination of iron metal and carbon non-metal) provide the high tensile strength required for suspension bridges, heavy-duty crane cables, skyscraper frameworks, and railway lines. Without high-strength metals and specialized alloys like titanium (vital for aerospace engineering) and zirconium (critical for nuclear power plants and atomic energy), space exploration, defense, and modern clean energy generation would be impossible.
Electrical and Energy Grid Architecture: High electrical conductivity in metals such as copper and aluminium enables national power grids to transmit electricity across thousands of miles into our homes, schools, and industries. Simultaneously, non-conducting materials like rubber gloves, plastic coverings on screwdrivers, and PVC wire insulations protect electricians and citizens from lethal electric shocks.
Biological Survival and Life Sciences: Non-metals are essential for biological existence. Elemental oxygen is required for cellular respiration in living organisms. Carbon serves as the fundamental elemental building block of all life, forming proteins, carbohydrates, and fats. Nitrogen is the main component of soil fertilizers that ensure global food security, while chlorine purifies municipal drinking water, and iodine solutions serve as critical medical antiseptics for wound disinfection.
Economic Sustainability and National Resource Management: Corrosion and rusting cause massive financial damage annually to national bridges, pipelines, ships, and buildings. Understanding protective treatments—such as painting, oiling, greasing, and galvanisation (applying a protective zinc coating)—saves billions of dollars. Furthermore, national initiatives in India to recycle iron and aluminium conserve natural ore reserves, reduce industrial carbon footprints, and promote environmental sustainability.

Activities

Textbook Activities

Malleability and Brittle Test (Activity 4.1): Under strict teacher supervision, place items such as a copper piece, aluminium piece, iron nail, coal piece, sulfur lump (gandhak), and wood block on a hard surface. Hammer each item carefully. Observe and record which materials flatten into thin sheets (malleable metals) and which shatter into pieces (brittle non-metals) or resist flattening (wood).
Investigating Sonority (Activity 4.2): Drop a metal spoon, a metallic coin, a piece of wood, and a lump of coal onto a hard floor from a uniform height. Note the clear, resonant ringing sound (sonority) produced by the metal objects compared to the dull, flat thuds of coal and wood.
Thermal Conduction Comparison (Activity 4.3): Fill a glass tumbler with hot water and submerge a metal spoon and a wooden spoon simultaneously. Touch the upper ends after a few minutes to observe how heat rapidly conducts through the metal spoon while the wooden handle remains cool, demonstrating that metals are good conductors of heat.
Electrical Conductivity Circuit Tester (Activity 4.4): Construct a simple circuit tester using a cell, wire, and light bulb. Insert test materials between the terminals: aluminium foil, iron nail, sulfur lump, copper wire, coal, dry wood, stone, rubber eraser, and nylon rope. Record which items complete the circuit and cause the bulb to glow (good conductors) versus those that block current (poor conductors).
Three-Bottle Iron Rusting Experiment (Activity 4.5): Set up three glass bottles labeled A, B, and C with scrubbed, shiny iron nails:
- Bottle A: Iron nail + silica gel (absorbs moisture to create dry air), sealed tightly.
- Bottle B: Iron nail + freshly boiled and cooled water (gas-free) + surface oil layer, sealed tightly.
- Bottle C: Iron nail partially submerged in water, left open to air. Leave undisturbed for 8–10 days to prove that both oxygen and water are required for rusting.
Magnesium Ribbon Combustion & Oxide Nature (Activity 4.6 – Demonstration): Clean a 3–4 cm magnesium ribbon with sandpaper, hold it with tongs, and ignite it over a spirit lamp. Collect the white magnesium oxide ash, dissolve it in warm water, and test with litmus paper to observe red litmus turning blue, proving metal oxides are basic.
Sulfur Deflagration & Acidic Oxide Test (Activity 4.7 – Demonstration in Fume Hood): Heat powdered sulfur in a long-handled deflagrating spoon until it burns, then lower it into a gas jar. Seal the jar, allow sulfur dioxide gas to collect, add a small volume of water, shake to form sulfurous acid, and test with litmus to observe blue litmus turning red, proving non-metal oxides are acidic.
Water Non-Reactivity of Non-Metals (Activity 4.8): Add sulfur powder to water in a glass tumbler to observe that non-metals generally do not react with water.

Experiential & Out-of-Book Learning Activities

Role-Play: The Great Elemental Court Debate: Organize a classroom debate with students assigned roles as key elements (Iron, Gold, Sodium, Oxygen, Carbon, Nitrogen, Mercury) defending why their specific element is the most important element in human history and modern technology.
Heritage Metal Art Exploration & Collage: Investigate traditional Indian metallurgical styles such as Dhokra, Bidriware, Pembarthi, and Kamrupi. Map the geographical origins of these crafts across Indian states and assemble a visual collage showcasing their techniques.
Smartphone Teardown & Element Audit: Research the internal components of modern smartphones to identify which metals (copper, gold, lithium, aluminium) and non-metals (silicon, oxygen) are utilized in microchips, batteries, and display screens.
Galvanisation and Protective Coating Simulation: Dip clean iron nails into various protective barriers (paint, oil, grease, clear varnish, and candle wax) and expose them to moist air alongside an untreated nail to evaluate rust prevention efficiency over two weeks.

Diagrams & Maps

Figure 4.1 & 4.2: Hammering an Iron Nail (Malleability setup)
- Labels: Hammer, Iron Nail, Hard Surface/Anvil, Impact Zone.
- Explanation: Illustrates the physical mechanical action where force transforms a solid cylindrical iron nail into a flattened shape without fracturing, demonstrating metallic malleability.
Figure 4.3: Conduction of Heat in Liquids Experiment
- Labels: Glass Tumbler, Hot Water, Metal Spoon (Hot Upper End), Wooden Spoon (Cool Upper End), Heat Transfer Arrows.
- Explanation: Depicts thermal energy transferring rapidly up the metallic lattice via thermal conduction, while the non-metallic wooden spoon blocks thermal flow.
Activity 4.4 Setup: Electric Circuit Tester
- Labels: Electric Cell/Battery, Connecting Wires, Switch, Light Bulb, Test Terminals/Clips, Test Specimen (Aluminium Foil / Sulfur / Copper Wire / Rubber Eraser).
- Explanation: Demonstrates electrical conductivity by closing the circuit through metallic conductors, causing the bulb filament to glow.
Figure 4.4a, 4.4b, 4.4c: The Three-Bottle Rusting Investigation Apparatus
- Labels:
  - Bottle A: Tight Cap, Thread, Iron Nail, Silica Gel, Dry Air Zone.
  - Bottle B: Tight Cap, Layer of Oil, Boiled & Cooled Water (Dissolved Air Removed), Fully Submerged Iron Nail.
  - Bottle C: Unstoppered Opening, Moist Air Zone, Water Level, Partially Submerged Iron Nail, Flaky Brown Rust Deposit.
- Explanation: Establishes controlled environmental variables showing that neither dry air alone nor air-free water causes rust; both water and oxygen are required for iron oxidation.
Figure 4.5 & 4.6: Combustion of Magnesium Ribbon and Basic Nature Test
- Labels: Tongs, Magnesium Ribbon (3–4 cm), Spirit Lamp Flame, Dazzling White Light, Watch Glass, White Powder (Magnesium Oxide – $\text{MgO}$), Warm Water Mixture, Red Litmus Paper turning Blue.
- Explanation: Shows the exothermic oxidation of magnesium metal into a basic oxide that generates hydroxide ions in aqueous solution.
Figure 4.7a, 4.7b, 4.7c, 4.7d: Sulfur Burning Deflagration Apparatus and Acidic Nature Test
- Labels: Deflagrating Spoon (or Improvised Wire-Wrapped Metallic Cap), Powdered Sulfur, Gas Jar / Tumbler, Jar Lid, Sulfur Dioxide Gas ($\text{SO}_2$), Water Layer, Sulfurous Acid Solution ($\text{H}_2\text{SO}_3$), Blue Litmus Paper turning Red.
- Explanation: Illustrates the non-metal combustion process forming an acidic gas that lowers solution pH upon dissolution in water.
Map of Ancient & Modern Indian Metallurgical Resources
- Labels: States rich in Iron ore, Gold mines, Aluminium (Bauxite) reserves, locations of historical heritage metal art centers (Dhokra, Bidriware, Pembarthi, Kamrupi), and the site of the Iron Pillar of Delhi.
- Explanation: Provides a geographical context mapping natural mineral resources and traditional craft centers across India.

The Exhaustive Sequence / Process / Timeline

[Phase 1: Ancient Civilisations & Metal Evolution]
       │
       ├─ Harappan Civilisation: Used Copper & Gold for utensils/jewellery; Iron unused
       ├─ Iron Age Transition: Iron tools developed (ploughs, axes, spades)
       ├─ Golden Age Metallurgy (~1600+ years ago): Chandragupta II era Iron Pillar of Delhi built
       └─ Modern Industrial Era: Global grids, aerospace alloys (Titanium), nuclear energy (Zirconium)

[Phase 2: Systematic Testing of Physical Properties]
       │
       ├─ Malleability Test: Metals flatten into sheets; non-metals break (brittle)
       ├─ Ductility Test: Metals pulled into wires (1g Gold -> 2km wire); non-metals shatter
       ├─ Sonority Test: Metals produce ringing sound; non-metals produce dull sounds
       ├─ Thermal Conduction: Metal lattice transfers heat fast; non-metal insulators block heat
       └─ Electrical Conduction: Free electron/charge flow in metals lights tester bulb

[Phase 3: Chemical Oxidation & Reaction Cascades]
       │
       ├─ Metal Reaction with Oxygen:
       │    Magnesium + Oxygen + Heat ➔ Magnesium Oxide (White Powder)
       │    Magnesium Oxide + Warm Water ➔ Basic Solution ➔ Red Litmus turns Blue
       │
       ├─ Non-Metal Reaction with Oxygen:
       │    Sulfur + Oxygen + Heat ➔ Sulfur Dioxide Gas
       │    Sulfur Dioxide Gas + Water ➔ Sulfurous Acid ➔ Blue Litmus turns Red
       │
       └─ Iron Rusting Mechanism:
            Iron + Water (Moisture) + Air (Oxygen) [Bottle C] ➔ Hydrated Iron Oxide (Rust)

Chronological and Logical Operational Sequences

The Historical Timeline of Indian Metallurgy:
- Stage A (Harappan Civilisation): Craftsmen worked primarily with copper and gold to create artistic ornaments, statues, and basic utensils. Iron was virtually unknown or unutilized.
- Stage B (Post-Harappan Agricultural Expansion): Iron extraction and forging techniques developed, producing robust agricultural implements like iron ploughs, axes, and trowels. This technological breakthrough increased agricultural yields and supported urban development.
- Stage C (Gupta Empire Metallurgy – ~1,600 Years Ago): Indian blacksmiths under Chandragupta II forged the 8-metre tall, 6,000 kg Iron Pillar of Delhi using advanced rust-resistant techniques.
- Stage D (Modern Industrial Science): Specialized application of elemental metals and alloys across electrical infrastructure (copper wires), aerospace (titanium), atomic energy (zirconium), and sustainable recycling pipelines (iron/aluminium).
The Scientific Sequence of Iron Rusting (Activity 4.5):
- Step 1: Prepare three iron nails, scrubbing away existing surface oxides using sandpaper until they display a shiny metallic lustre.
- Step 2 (Bottle A setup): Suspend Nail 1 in Bottle A containing silica gel pouches to strip all humidity from the air, then cap the bottle tightly. Result: No rust forms after 8–10 days due to the absence of water.
- Step 3 (Bottle B setup): Suspend Nail 2 in Bottle B filled with boiled, cooled water (which expels dissolved atmospheric gases) and seal the water surface with an oil layer before capping tightly. Result: No rust forms after 8–10 days due to the absence of dissolved oxygen.
- Step 4 (Bottle C setup): Partially submerge Nail 3 in water inside an open, unstoppered Bottle C exposed directly to room air. Result: A thick, flaky brown deposit (rust) forms on the nail surface after 8–10 days.
- Deduction: Rusting requires the simultaneous presence of both water vapor/moisture and oxygen gas.
The Chemical Combustion and Nature Identification Cascades:
- Cascade A (Metal Oxidation – Magnesium):
  1. Rub a 3–4 cm magnesium ribbon with sandpaper to remove protective oxide films.
  2. Clamp with tongs and ignite using a spirit lamp or candle flame.
  3. Observe the metal burning with a dazzling white flame to form a white powder: $\text{Magnesium} + \text{Oxygen} \rightarrow \text{Magnesium Oxide}$.
  4. Collect the white powder in a watch glass, add warm water, and stir to form a solution.
  5. Apply red litmus paper—the red paper turns blue, confirming that metal oxides are basic.
- Cascade B (Non-Metal Oxidation – Sulfur):
  1. Place powdered sulfur into a long-handled deflagrating spoon and heat over an open flame.
  2. As soon as sulfur ignites, lower the spoon into a gas jar and seal the jar lid to trap the fumes.
  3. Observe the formation of sulfur dioxide gas: $\text{Sulfur} + \text{Oxygen} \rightarrow \text{Sulfur Dioxide}$.
  4. Remove the spoon, pour in a small volume of water, replace the lid, and shake vigorously.
  5. The gas dissolves to form sulfurous acid: $\text{Sulfur Dioxide} + \text{Water} \rightarrow \text{Sulfurous Acid}$.
  6. Apply blue litmus paper—the blue paper turns red, confirming that non-metal oxides are acidic.

Comprehensive Vocabulary (The Word List)

Metal – A class of elements that are generally hard, lustrous, malleable, ductile, sonorous, and good conductors of heat and electricity – Used in the chapter to classify elements like iron, copper, aluminium, gold, sodium, and magnesium.
Non-metal – A class of elements that are typically non-lustrous, soft or brittle, non-malleable, non-ductile, non-sonorous, and poor conductors of heat and electricity – Referenced as elements like sulfur, phosphorus, oxygen, nitrogen, carbon, chlorine, and iodine.
Metallic Lustre – The shiny, reflective appearance characteristic of clean metal surfaces – Referenced as a primary visual property used to distinguish metals like copper and aluminium from non-metals like coal and sulfur.
Malleability – The physical property of a material that allows it to be hammered or beaten into thin sheets without fracturing – Used to describe how iron, copper, gold, silver, and aluminium can be beaten into thin sheets or foils.
Brittle – The property of a material that causes it to shatter or break into pieces when struck with a hammer – Referenced to explain the behavior of non-metals like coal and sulfur under mechanical impact.
Ductility – The physical property of a material that enables it to be drawn or stretched into thin wires – Referenced to explain how copper wires are drawn for electrical fittings and gold is drawn into long threads.
Sonority – The physical property of metals that allows them to produce a clear, resonant, ringing sound when struck – Referenced as the property responsible for the sound of school bells, ghungroos, coins, and stringed instruments.
Thermal Conduction – The transfer of thermal energy through a material from a region of higher temperature to lower temperature – Referenced in Activity 4.3 to explain why metal cooking utensils get hot throughout.
Conductor – A material that permits the easy transfer of thermal energy or electric current through its structure – Referenced to categorize metals like aluminium, iron, and copper as good conductors of heat and electricity.
Poor Conductor (Insulator) – A material that resists or blocks the flow of heat or electricity – Referenced to describe materials like wood, rubber, plastic, sulfur, and coal.
Rusting – The specific chemical process where iron reacts with moist air (water and oxygen) over time to form a brown coating – Referenced in Activity 4.5 as a major cause of structural damage to iron infrastructure.
Corrosion – The gradual deterioration and discolouration of a metal surface caused by atmospheric chemical reactions with air, moisture, or chemicals – Referenced as the general phenomenon that includes iron rusting, green tarnishing on copper, and black tarnishing on silver.
Galvanisation – The industrial process of applying a thin protective layer of zinc metal over iron objects to prevent rusting – Referenced as an essential rust prevention technique.
Iron Pillar of Delhi – An ancient 8-metre-tall, 6,000 kg iron structure built during the reign of Chandragupta II over 1,600 years ago – Referenced as an example of ancient Indian metallurgical mastery due to its rust resistance.
Deflagrating Spoon – A long-handled metal spoon with a small cup used in laboratories to safely burn substances like sulfur inside gas jars – Used in Activity 4.7 to contain burning sulfur.
Basic Oxide – A metallic oxide that reacts with water to form a basic solution that turns red litmus paper blue – Referenced when magnesium oxide powder is dissolved in water.
Acidic Oxide – A non-metallic oxide that reacts with water to form an acidic solution that turns blue litmus paper red – Referenced when sulfur dioxide gas is dissolved in water.
Element – A pure substance that cannot be broken down into simpler substances by chemical means – Referenced as the fundamental classification containing 118 known building blocks of matter.
Alloy – A uniform mixture composed of two or more metals, or a metal and a non-metal – Used to describe steel (iron + carbon) and specialty metal mixtures used in utensils, technology, and aerospace.
Silica Gel – A chemical substance packaged in small porous pouches that actively absorbs moisture to create a dry environment – Used in Activity 4.5 (Bottle A) to strip humidity from sealed air.
Sodium – A highly reactive, soft metal that can be cut with a knife and is stored in kerosene to prevent explosive reactions with air and water – Referenced as an exceptional soft metal.
Phosphorus – A non-metal that spontaneously catches fire upon exposure to atmospheric air and must be stored underwater – Referenced as a highly reactive non-metal.
Titanium – A strong, light metal heavily utilized in advanced aerospace engineering – Referenced in the Science and Society section.
Zirconium – A specialty metal vital for applications in nuclear power and atomic energy technology – Referenced in the Science and Society section.
Tincture of Iodine / Iodine – A non-metallic element applied topically as an antiseptic solution to disinfect cuts and wounds – Referenced as an essential medical non-metal.

Teacher’s Chapter Checklist

[ ] Target 1: Physical Property Identification
- [ ] Verify students can define and distinguish Metallic Lustre vs. non-lustrous materials.
- [ ] Ensure mastery of Malleability (beating into sheets) and identify silver/aluminium foils as practical applications.
- [ ] Confirm understanding of Brittle behavior in non-metals (coal, sulfur) versus non-brittle wood.
- [ ] Verify comprehension of Ductility (drawing into wires) and recall that 1 gram of gold yields a 2 km wire.
- [ ] Teach Sonority and identify sonorous everyday objects (bells, ghungroos, coins).
- [ ] Explain exceptions to general physical rules: Sodium and Potassium are soft metals cut with a knife; Mercury is a liquid metal at room temperature.
[ ] Target 2: Thermal and Electrical Conduction Mechanics
- [ ] Conduct Activity 4.3 to demonstrate heat conduction through metal vs. wooden spoons.
- [ ] Build circuit testers (Activity 4.4) to classify materials as good conductors (aluminium, copper, iron) or poor conductors (sulfur, coal, wood, rubber, plastic, nylon).
- [ ] Connect electrical conduction concepts to real-world safety gear (rubber gloves, plastic screwdriver handles).
[ ] Target 3: Corrosion & The Chemistry of Iron Rusting
- [ ] Set up the 8–10 day three-bottle experiment (Activity 4.5) with silica gel (Bottle A), boiled water + oil (Bottle B), and open air + water (Bottle C).
- [ ] Ensure students conclude that rusting strictly requires both oxygen and moisture.
- [ ] Define Corrosion generally and list specific examples: brown iron rust, green copper coating, black silver coating.
- [ ] Detail rust prevention strategies: painting, oiling, greasing, and galvanisation (zinc coating).
- [ ] Integrate historical achievements: discuss the rust-resistant Iron Pillar of Delhi built under Chandragupta II (>1600 years old, 8m tall, >6000 kg weight).
[ ] Target 4: Chemical Oxidation of Metals vs Non-Metals
- [ ] Demonstrate burning of magnesium ribbon (Activity 4.6), noting the dazzling white flame and white powder formation ($\text{MgO}$).
- [ ] Prove basic nature of metal oxides by showing aqueous $\text{MgO}$ turns red litmus blue.
- [ ] Demonstrate burning sulfur in a deflagrating spoon (Activity 4.7) inside a fume hood.
- [ ] Dissolve $\text{SO}_2$ gas in water to form sulfurous acid and prove non-metal oxides are acidic (turns blue litmus red).
- [ ] Explain storage precautions for extreme reactivity: Sodium stored in kerosene; Phosphorus stored in water.
[ ] Target 5: Fundamental Classification & Societal Applications
- [ ] Define an Element as a fundamental substance that cannot be chemically simplified, noting there are 118 known elements.
- [ ] Clarify that items like plastic, wood, glass, rubber, and paper are not elements.
- [ ] Detail key non-metal functions: Oxygen for respiration, Carbon as the building block of life, Nitrogen for fertilizers, Chlorine for water purification, and Iodine as a wound antiseptic.
- [ ] Define Alloys (e.g., steel = iron + carbon) and list technological metals (Titanium in aerospace, Zirconium in atomic energy).
- [ ] Discuss environmental sustainability through Indian recycling efforts for iron and aluminium.

Ready-Reckoner Student Revision Notes

1. Core Definitions & Physical Properties Summary Table

Metals: Materials that are generally hard, lustrous, malleable, ductile, sonorous, and efficient conductors of both heat and electricity.
Non-metals: Materials that are typically dull, soft or brittle, non-malleable, non-ductile, non-sonorous, and poor conductors of heat and electricity.
Element: A pure substance that cannot be broken down into simpler substances by any chemical reactions. There are 118 known elements forming all matter in the universe. (Note: Plastic, glass, wood, rubber, and paper are NOT elements.)

Physical Property	Metals	Non-Metals
Appearance / Lustre	Lustrous (Metallic lustre; e.g., Copper, Aluminium, Gold).	Non-lustrous / Dull (e.g., Coal, Sulfur).
Hardness & State	Generally Hard & Solid. Exceptions: Sodium (Na) & Potassium (K) are soft enough to cut with a knife. Mercury (Hg) is liquid at room temperature.	Generally Soft Solids or Gases. Exception: Soft/brittle solids break easily.
Malleability	Malleable (Can be beaten into thin sheets without breaking). Examples: Silver foil on sweets, Aluminium food wrapping foil. Most malleable: Gold & Silver.	Brittle / Non-malleable (Shatter into pieces when struck with a hammer; e.g., Sulfur, Coal).
Ductility	Ductile (Can be drawn into thin wires). Fact: 1 gram of Gold can be drawn into a 2 km-long wire.	Non-ductile (Cannot be drawn into wires).
Sonority	Sonorous (Produce a deep, clear ringing sound when struck; e.g., school bells, ghungroos, coins).	Non-sonorous (Produce dull, flat thuds when dropped).
Thermal Conductivity	Good Conductors of Heat (e.g., metal cooking vessels).	Poor Conductors / Insulators (e.g., wooden handles).
Electrical Conductivity	Good Conductors of Electricity (e.g., Copper, Aluminium, Iron).	Poor Conductors of Electricity (e.g., Sulfur, Coal, Rubber, Wood, Nylon).

2. Chemical Properties & Reaction Mechanics

A. Reaction with Oxygen

Metals: React with oxygen to form metal oxides, which are BASIC in nature.
- Example: Magnesium ribbon (cleaned with sandpaper) burns with a dazzling white flame in air to form Magnesium Oxide powder: \[\text{Magnesium (Mg)} + \text{Oxygen (O}_2\text{)} \xrightarrow{\text{Heat}} \text{Magnesium Oxide (MgO)}\]
- Litmus Test: When $\text{MgO}$ is dissolved in warm water, the solution turns Red Litmus Paper to Blue.
Non-metals: React with oxygen to form non-metal oxides, which are ACIDIC in nature.
- Example: Powdered sulfur heated in a deflagrating spoon burns to produce Sulfur Dioxide gas: \[\text{Sulfur (S)} + \text{Oxygen (O}_2\text{)} \xrightarrow{\text{Heat}} \text{Sulfur Dioxide (SO}_2\text{)}\]
- Acid Formation: Dissolving $\text{SO}_2$ gas in water forms Sulfurous Acid: \[\text{Sulfur Dioxide (SO}_2\text{)} + \text{Water (H}_2\text{O)} \rightarrow \text{Sulfurous Acid (H}_2\text{SO}_3\text{)}\]
- Litmus Test: Sulfurous acid solution turns Blue Litmus Paper to Red.

B. Reaction with Water & Storage Anomalies

Metals: Vary widely in reactivity.
- Sodium (Na) reacts explosively and vigorously with oxygen and water, generating large amounts of heat. Therefore, it is kept safely stored under kerosene.
Non-metals: Generally do NOT react with water.
- Phosphorus is a highly reactive non-metal that catches fire spontaneously when exposed to air. Therefore, it is kept safely stored under water.

3. Corrosion, Rusting, and Ancient Indian Metallurgy

A. Mechanics of Iron Rusting

Rust Definition: A reddish-brown flaky deposit formed on iron when exposed to moist air.
Essential Conditions: Rusting strictly requires BOTH Oxygen (Air) and Water (Moisture).
Experimental Proof (Activity 4.5):
- Bottle A (Dry Air): Iron Nail + Silica Gel + Sealed Cap $\rightarrow$ NO RUST (No moisture).
- Bottle B (Air-Free Water): Iron Nail + Boiled/Cooled Water + Surface Oil Layer + Sealed Cap $\rightarrow$ NO RUST (No oxygen).
- Bottle C (Moist Air): Iron Nail + Water + Open to Air $\rightarrow$ RUST FORMS (Both air and water present).

B. General Corrosion & Prevention Methods

Corrosion: The gradual chemical breakdown and surface deterioration of metals caused by air, water, or atmospheric chemicals.
- Copper Corrosion: Develops a characteristic green coating over time.
- Silver Corrosion: Develops a characteristic black coating over time.
Rust Prevention Techniques:
1. Painting surface barriers.
2. Applying protective oil or grease layers.
3. Galvanisation: Applying a protective layer of zinc metal over iron structures.

C. Historical Milestone: The Iron Pillar of Delhi

Location & Age: Erected in Delhi during the reign of Chandragupta II, over 1,600 years ago.
Dimensions: Height = 8 metres; Weight = over 6,000 kilograms.
Historical Significance: Despite over 16 centuries of exposure to severe outdoor weather, rain, and heat, it displays virtually no rust, serving as global proof of advanced ancient Indian metallurgical skill.

4. Real-World Applications & Uses of Elements

A. Uses of Non-Metals in Daily Life & Industry

Oxygen: Required for respiration and survival of all living organisms.
Carbon: The elemental building block of life; forms proteins, fats, and carbohydrates essential for growth.
Nitrogen: Essential plant nutrient used extensively in manufacturing agricultural fertilizers and industrial chemicals.
Chlorine: Utilized globally for municipal water purification and water treatment.
Iodine: Used to prepare antiseptic solutions (such as tincture of iodine) applied to disinfect wounds.

B. Industrial Metals, Alloys, and Sustainability

Steel: An alloy of iron (metal) and carbon (non-metal) providing extraordinary strength for suspension bridges, cranes, and structural frameworks.
Titanium: High-strength, lightweight metal crucial for modern aerospace technology.
Zirconium: Specialty metal essential for atomic energy and nuclear power plants.
Indian Metal Art Styles: Heritage metal crafts including Dhokra, Bidriware, Pembarthi, and Kamrupi.
Recycling & Environment: Active recycling of iron and aluminium in India reduces industrial waste, saves raw ore, and promotes long-term ecological sustainability.

QUESTIONS :

Master Question Bank: The World of Metals and Non-metals

1. The “Hidden” In-Text Questions (Mid-Chapter Extraction)

Section 4.1: Properties of Materials & Malleability

Q1. What specific daily-use items and agricultural tools do village ironsmiths forge using red-hot iron, wood, and coal furnaces, as observed by Yashwant and Anandi during their visit to Sudarshan uncle?

Q2. How does the physical effect of hammering an iron nail or copper piece differ from the effect of hammering a piece of coal or a lump of sulfur?

Q3. What are the exceptions to the general rule that metals are hard solids, and which metal exists in a liquid state at room temperature?

Q4. According to the ‘Holistic Lens’ section, why was iron hardly used by the ancient Harappans despite their proficiency with copper and gold, and how did iron later transform agriculture in India?

Section 4.1.2: Ductility

Q5. What is ductility, and how does the ductile nature of gold demonstrate an extreme physical capability in terms of wire length per gram?

Q6. What compositional materials make up steel wire ropes, and why are these ropes specifically chosen for suspension bridges and heavy-duty cranes?

Section 4.1.3: Sonority

Q7. Define sonority, and list three distinct real-world or cultural applications where the sonorous nature of metals is utilized.

Section 4.1.4: Conduction of Heat

Q8. In Activity 4.3, when a metal spoon and a wooden spoon are simultaneously immersed in hot water, why does only the upper end of the metal spoon become hot, and how does this govern utensil design?

Section 4.1.5: Conduction of Electricity

Q9. Explain why electricians wear rubber gloves and rubber shoes, and why screwdriver handles are encased in plastic, based on the electrical conductivity test in Activity 4.4.

Section 4.2: Effect of Air and Water on Metals (Iron & Corrosion)

Q10. Based on the three-bottle investigation (Activity 4.5), explain the specific atmospheric conditions required for an iron nail to form rust, detailing the role of silica gel in Bottle A and boiled water with oil in Bottle B.

Q11. What green and black coatings appear on copper and silver objects respectively when exposed to atmospheric air, and what term describes this general surface deterioration?

Q12. Describe the physical dimensions, historical age, and technological significance of the Iron Pillar of Delhi built during the reign of Chandragupta II.

Section 4.3 & 4.4: Reaction of Metals and Non-metals with Air and Water

Q13. Describe the visual observations when a magnesium ribbon burns in air, the formula of the ash formed, and the chemical nature of its aqueous solution when tested with litmus paper.

Q14. Why is sodium metal stored under kerosene, while elemental phosphorus is stored under water?

Q15. Outline the procedure for burning sulfur in a deflagrating spoon (Activity 4.7) and explain why the resulting sulfurous acid turns blue litmus paper red.

Q16. What is an element, how many elements are currently known, and why are materials like plastic, glass, wood, rubber, and paper not classified as metals or non-metals?

Section 4.5 & Science & Society: Applications of Non-Metals and Metals

Q17. Detail the essential biological and daily-life roles played by the non-metals oxygen, carbon, nitrogen, chlorine, and iodine.

Q18. Name two specialized metals used in aerospace technology and atomic energy, and explain the significance of metal recycling initiatives in India.

2. The Textbook Exercise Integration (Back-of-Chapter)

The following questions are extracted directly from the ‘Let Us Enhance Our Learning’ section at the end of the chapter:

Q1. Which metal is commonly used to make food packaging materials as it is cheaper, and its thin sheets can be folded easily into any shape? (i) Aluminium (ii) Copper (iii) Iron (iv) Gold

Q2. Which of the following metal catches fire when it comes in contact with water? (i) Copper (ii) Aluminium (iii) Zinc (iv) Sodium

Q3. State with reason(s) whether the following statements are True [T] or False [F]. (i) Aluminium and copper are examples of non-metals used for making utensils and statues. [ ] (ii) Metals form oxides when combined with oxygen, the solution of which turns blue litmus paper to red. [ ] (iii) Oxygen is a non-metal essential for respiration. [ ] (iv) Copper vessels are used for boiling water because they are good conductors of electricity. [ ]

Q4. Why are only a few metals suitable for making jewellery?

Q5. Match the uses of metals and non-metals given in Column I with the jumbled names of metals and non-metals given in Column II.

Column I	Column II
(i) Used in electrical wiring	(a) ENXYGO
(ii) Most malleable and ductile	(b) NECOHIRL
(iii) Living organisms cannot survive without it.	(c) PEPORC
(iv) Plants grow healthy when fertilisers containing it are added to the soil.	(d) TENGOINR
(v) Used in water purification	(e) OGDL

Q6. What happens when oxygen reacts with magnesium and sulfur. What are the main differences in the nature of products formed?

Q7. Complete the following flow chart: [Substance] + Air + Heat $\rightarrow$ Ash + Water $\rightarrow$ [Solution] $\rightarrow$ Add blue and red litmus solutions separately $\rightarrow$ Change in blue litmus solution / Change in red litmus solution $\rightarrow$ Blue.

Q9. You are provided with three iron nails, each dipped in oil, water and vinegar. Which iron nail will not rust, and why?

Q10. How do the different properties of metals and non-metals determine their uses in everyday life?

Q11. One of the methods of protecting iron from getting rusted is to put a thin coating of zinc metal over it. Since sulfur does not react with water, can it be used for this purpose? Justify your answer.

Q12. An ironsmith heats iron before making tools. Why is heating necessary in this process?

3. Exhaustive Objective Bank (The Factual Baseline)

20+ Multiple-Choice Questions (MCQs)

Q1. Which of the following tools made by ironsmiths is used specifically as a farming implement for digging or turning soil?

A) Tawa B) Chimta C) Phawra D) Balti

Q2. What term describes the shiny, reflective appearance displayed by clean surfaces of metals such as copper, aluminium, and iron?

A) Sonority B) Metallic Lustre C) Ductility D) Viscosity

Q3. What happens when a pea-sized lump of sulfur or a piece of coal is struck hard with a hammer?

A) It flattens into a thin sheet B) It shatters into small brittle pieces C) It draws out into a fine wire D) It emits a loud ringing sound

Q4. Which two metals are so exceptionally soft that they can be cut easily using a knife?

A) Gold and Silver B) Sodium and Potassium C) Iron and Copper D) Aluminium and Magnesium

Q5. Which metal remains in a liquid state at room temperature and is utilized in thermometers?

A) Sodium B) Zinc C) Mercury D) Platinum

Q6. Exactly how long a wire can be drawn from a single gram of gold due to its extraordinary ductility?

A) 200 metres B) 1 kilometre C) 2 kilometres D) 5 kilometres

Q7. Steel wire ropes used in suspension bridges and cranes are composed of which combination of elements?

A) Iron metal and Carbon non-metal B) Copper metal and Zinc metal C) Aluminium metal and Sulfur non-metal D) Gold metal and Silver metal

Q8. Which musical instruments utilize metal wires owing to the property of ductility and tension?

A) Flute and Tabla B) Veena and Sitar C) Harmonium and Dholak D) Shehnai and Nagada

Q9. In Activity 4.3, why does a wooden spoon fail to become hot when immersed in boiling water?

A) Wood is a good thermal conductor B) Wood absorbs all heat energy permanently C) Wood is a poor conductor of heat D) Wood chemically reacts with water

Q10. In the electric circuit tester experiment (Activity 4.4), which of the following materials causes the bulb to glow?

A) Lump of sulfur B) Rubber eraser C) Nylon rope D) Copper wire

Q11. What is the precise function of silica gel placed inside Bottle A during the iron rusting investigation (Activity 4.5)?

A) To supply oxygen gas B) To absorb moisture and keep air dry C) To coat the iron nail with zinc D) To prevent nitrogen from reacting

Q12. In Bottle B of Activity 4.5, why is water freshly boiled and then covered with a layer of oil?

A) To increase water temperature B) To dissolve atmospheric oxygen C) To expel dissolved gases and block atmospheric air D) To accelerate rust formation

Q13. What chemical name and color describe the coating formed on iron objects after prolonged exposure to moist air?

A) Basic Copper Carbonate (Green) B) Hydrated Iron Oxide / Rust (Brown) C) Silver Sulfide (Black) D) Zinc Oxide (White)

The process of applying a thin protective coating of zinc metal over iron objects to prevent rusting is called:
A) Malleability B) Galvanisation C) Deflagration D) Ductility

Q15. How tall is the ancient Iron Pillar of Delhi, and approximately how much does it weigh?

A) 5 metres tall, 2000 kilograms B) 8 metres tall, over 6000 kilograms C) 12 metres tall, 10000 kilograms D) 15 metres tall, 4000 kilograms

Q16. During Activity 4.6, burning a magnesium ribbon produces a dazzling flame of what color, forming what product?

A) Dazzling yellow flame forming Magnesium Sulfide B) Dazzling white flame forming Magnesium Oxide ash C) Blue flame forming Magnesium Carbonate D) Red flame forming pure Magnesium metal

Q17. When magnesium oxide powder is dissolved in warm water and tested with litmus paper, what color change occurs?

A) Blue litmus turns Red B) Red litmus turns Blue C) Phenolphthalein turns colorless D) Universal indicator turns yellow

Q18. Why is elemental sodium metal stored submerged under kerosene?

A) It evaporates instantly in air B) It reacts vigorously with oxygen and water, generating intense heat C) It absorbs kerosene to remain malleable D) It dissolves in atmospheric moisture

Q19. Burning powdered sulfur in a deflagrating spoon yields sulfur dioxide gas, which dissolves in water to form:

A) Sulfuric acid B) Sulfurous acid C) Sodium hydroxide D) Hydrogen sulfide

When sulfurous acid solution is tested with litmus paper, what observation confirms its chemical nature? A) Red litmus paper turns Blue B) Blue litmus paper turns Red C) Red litmus paper turns Yellow D) Blue litmus paper remains unchanged

Q21. Why is elemental phosphorus stored underwater in laboratories?

A) It dissolves in water to form fertilizer B) It catches fire spontaneously when exposed to atmospheric air C) It reacts with water to release oxygen gas D) It turns into a liquid metal in water

Q22. Total how many chemical elements are currently known to exist as basic building blocks of matter?

A) 92 B) 100 C) 108 D) 118

Q23. Which non-metal is applied on cuts and wounds as an effective antiseptic solution?

A) Chlorine B) Nitrogen C) Iodine D) Carbon

Q24. Which specialized metals are critical for advanced aerospace engineering and atomic energy technology respectively?

A) Iron and Copper B) Titanium and Zirconium C) Gold and Silver D) Sodium and Potassium

15 Fill-in-the-Blanks

Q1. The property by which metals can be beaten into thin sheets without fracturing is called ________.

Q2. Ancient Harappan artisans crafted ornaments and utensils using copper and ________, but hardly ever used iron.

Q3. Gold and ________ are recognized as the two most malleable metals known.

Q4. Materials like coal and sulfur shatter into pieces upon hammering because they are ________.

Q5. The property that enables metals to be drawn into long, thin wires is known as ________.

Q6. The property of metals to produce a deep, clear ringing sound when struck is termed ________.

Q7. Materials that permit heat or electricity to pass through them easily are classified as ________.

Q8. Electricians wear rubber gloves because rubber is a ________ conductor of electricity.

Q9. The brown flaky deposit formed on iron objects upon exposure to moist air is called ________.

Q10. The gradual surface deterioration of metals caused by atmospheric air, water, or chemicals is known as ________.

Q11. The Iron Pillar of Delhi was erected during the reign of ________ more than 1600 years ago.

Q12. Metallic oxides dissolve in water to form solutions that are ________ in nature.

Q13. Non-metallic oxides dissolve in water to produce solutions that are ________ in nature.

Q14. Non-metals do not react with ________, making it safe to store reactive phosphorus under it.

Q15. A fundamental pure substance that cannot be broken down into simpler chemical substances is an ________.

10 True/False Questions

(Instruction: State whether the statement is True [T] or False [F]. If False, correct the statement).

Q1. All metals exist as hard solids at room temperature. (If False, correct the statement)

Q2. Wood is classified as a malleable material because it can be shaped into furniture without shattering. (If False, correct the statement)

Q3. Coal and sulfur can easily be drawn into electrical transmission wires due to high ductility. (If False, correct the statement)

Q4. Metals are good conductors of heat, whereas wood and plastic are poor conductors. (If False, correct the statement)

Q5. Iron nails require only dry air to undergo rusting inside sealed glass containers. (If False, correct the statement)

Q6. Silver objects develop a characteristic green coating when exposed to atmospheric air over time. (If False, correct the statement)

Q7. Magnesium oxide solution turns red litmus paper blue, proving that metal oxides are basic in nature. (If False, correct the statement)

Q8. Non-metal oxides dissolve in water to form basic solutions that turn red litmus paper blue. (If False, correct the statement)

Q9. Materials like plastic, glass, rubber, and paper are classified as non-metallic elements. (If False, correct the statement)

Q10. Chlorine is a non-metallic element widely used in municipal water purification systems. (If False, correct the statement)

4. Subjective & Competency Bank (Higher-Order Thinking)

(Note: Every question in this section is written strictly on a single line).

10 Short-Answer Questions

Q1. Why does an ironsmith heat an iron block to a red-hot state before beating it with a heavy hammer to make tools like axes or spades?

Q2. Explain how malleability is commercially exploited in the food packaging industry and sweet confectionery decorations.

Q3. Why are copper and aluminium preferred over other materials for domestic and industrial electrical wiring?

Q4. Explain why school bells, temple bells, and ghungroos are fabricated from metals rather than wood or compressed coal.

Q5. Why are cooking utensils made of metals like copper or aluminium while their handles are covered with wood or tough plastic?

Q6. How does silica gel prevent iron nails from developing brown rust deposits inside sealed containers?

Q7. Explain why boiling water and adding a surface layer of oil prevents iron nails from rusting in Activity 4.5.

Q8. Why must elemental sodium be kept submerged under kerosene oil in chemistry laboratories?

Q9. How can a student experimentally demonstrate that non-metallic oxides are acidic using burning sulfur and litmus paper?

Q10. Why are materials such as glass, plastic, wood, and paper excluded from classification as metallic or non-metallic elements?

5 Scenario-Based / Competency Questions

Q1. An electrician is fixing an overhead power connection in a residential colony. He uses a metal screwdriver with a plastic handle, wears thick rubber gloves, and stands on a wooden platform. Identify the conductors and insulators in this scenario and explain how this setup prevents electrical accidents.

Q2. A museum curator notices that a 19th-century iron anchor stored outdoors is covered in flaky brown rust, whereas a nearby ancient copper statue has developed a dull green surface film. Diagnose the chemical phenomena affecting both artifacts, state the atmospheric factors involved, and suggest restoration/protection methods.

Q3. A laboratory assistant accidentally left a bottle of sodium and a jar of white phosphorus open on a workbench near an open window on a humid day. Predict the chemical hazards that would occur for each substance and prescribe the correct storage protocols.

Q4. A farmer tests two soil samples: Field A yields basic ash when plant waste is burned, while Field B receives fertilizers manufactured from atmospheric nitrogen and sulfur compounds. Explain how non-metallic and metallic chemical inputs influence agricultural soil chemistry and crop growth.

Q5. An aerospace engineer is designing a lightweight, high-temperature casing for a jet turbine engine, while a civil engineer is selecting structural cables for a long-span suspension bridge. Identify the specific metal or alloy choices suitable for each application based on property requirements described in the chapter.

5 Long-Answer / Essay Questions

Q1. Detail the comprehensive experimental setup, procedural steps, observations, and conclusions of the three-bottle investigation (Activity 4.5) used to establish the precise atmospheric conditions necessary for iron rusting.

Q2. Compare and contrast the physical properties of metals and non-metals across seven key parameters: appearance/lustre, hardness/state, malleability, ductility, sonority, thermal conductivity, and electrical conductivity, highlighting all notable exceptions.

Q3. Describe the step-by-step experimental procedures for investigating the combustion of magnesium ribbon (metal) and sulfur powder (non-metal), write the word equations for all chemical reactions, and explain how litmus testing proves the chemical nature of their respective oxides.

Q4. Trace the historical evolution and societal impact of metallurgy in India, from Harappan craftwork through the Iron Age agricultural revolution to the engineering marvel of Chandragupta II’s Iron Pillar of Delhi and modern recycling sustainability practices.

Q5. Write an exhaustive essay detailing the indispensable roles played by non-metallic elements (oxygen, carbon, nitrogen, chlorine, iodine, phosphorus) in biological survival, agricultural food security, public health, and medicine.

5. The Master Answer Key & Marking Rubric

Section 1: In-Text Questions Answer Key

Q1 Answer: Tawas (flat pans), baltis (buckets), chimtas (tongs), phawras (spades), kulhadis (axes), khurpis (trowels), and jelees (rakes) made from iron metal heated over coal furnaces.
Q2 Answer: Iron and copper flatten into thin sheets without breaking (malleable), whereas coal and sulfur break into brittle pieces.
Q3 Answer: Soft metals cut with a knife: Sodium and Potassium. Liquid metal at room temperature: Mercury.
Q4 Answer: Harappans lacked iron technology (used copper/gold). Iron tools like ploughs developed later, boosting agricultural efficiency and civilisational growth.
Q5 Answer: Ductility is the property to be drawn into wires. 1 gram of gold can yield a 2 km-long wire.
Q6 Answer: Mixture of iron (metal) and carbon (non-metal). High tensile strength enables lifting heavy loads in bridges and cranes.
Q7 Answer: Property of producing a ringing sound when struck. Applications: School bells, ghungroos, stringed musical instrument wires.
Q8 Answer: Metals are good thermal conductors; wood is a poor conductor. Heat transfers along the metal spoon to its top.
Q9 Answer: Rubber and plastic are poor electrical conductors (insulators), protecting workers from electric shock.
Q10 Answer: Rusting requires both air (oxygen) and water (moisture). Silica gel removes moisture (dry air = no rust); boiled water + oil removes dissolved air (no oxygen = no rust).
Q11 Answer: Copper forms a green coating; silver forms a black coating. The process is corrosion.
Q12 Answer: Built during Chandragupta II reign (>1600 years ago), 8m height, >6000 kg weight. Resists rusting due to ancient metallurgical mastery.
Q13 Answer: Burns with a dazzling white flame forming white powder (Magnesium Oxide – $\text{MgO}$). Solution in warm water turns red litmus blue (basic oxide).
Q14 Answer: Sodium reacts explosively with air and water (stored in kerosene). Phosphorus catches fire spontaneously in air (stored in water).
Q15 Answer: Sulfur burns in air to form sulfur dioxide gas ($\text{SO}_2$), which dissolves in water to form sulfurous acid ($\text{H}_2\text{SO}_3$). Sulfurous acid turns blue litmus red (acidic oxide).
Q16 Answer: An element is a pure substance that cannot be broken down chemically. 118 elements exist. Plastic, glass, wood, rubber, paper are not elements.
Q17 Answer: Oxygen (respiration), Carbon (building block of proteins/fats/carbohydrates), Nitrogen (fertilizers/plants), Chlorine (water purification), Iodine (antiseptic).
Q18 Answer: Aerospace: Titanium; Atomic energy: Zirconium. Recycling iron and aluminium minimizes waste and conserves natural resources.

Section 2: Back-of-Chapter Textbook Exercises Answer Key

Q1 Answer: (i) Aluminium.
Q2 Answer: (iv) Sodium.
Q3 Answer: (i) False [F]. Corrected: Aluminium and copper are metals used for making utensils and statues. (ii) False [F]. Corrected: Metal oxides are basic and turn red litmus paper to blue. (iii) True [T]. (iv) False [F]. Corrected: Copper vessels are used because copper is a good conductor of heat.
Q4 Answer: Only a few metals like gold and silver are suitable for jewellery because they are highly malleable, ductile, possess brilliant lustre, and are non-reactive (do not corrode easily).
Q5 Answer: (i) Used in electrical wiring $\rightarrow$ (c) PEPORC (COPPER) (ii) Most malleable and ductile $\rightarrow$ (e) OGDL (GOLD) (iii) Living organisms cannot survive without it $\rightarrow$ (a) ENXYGO (OXYGEN) (iv) Plants grow healthy when fertilisers containing it are added $\rightarrow$ (d) TENGOINR (NITROGEN) (v) Used in water purification $\rightarrow$ (b) NECOHIRL (CHLORINE)
Q6 Answer:
- Magnesium + Oxygen $\rightarrow$ Magnesium Oxide (Basic oxide; turns red litmus blue).
- Sulfur + Oxygen $\rightarrow$ Sulfur Dioxide $\xrightarrow{+\text{Water}}$ Sulfurous Acid (Acidic oxide; turns blue litmus red).
Q7 Answer:
- [Substance] = Magnesium
- [Solution] = Magnesium oxide in water
- Change in blue litmus = No change
- Change in red litmus = Turns Blue
Q8 Answer: Copper or Iron would be the ideal choice because they are metals and good conductors of heat. Sulfur and coal are brittle non-metals; plastic, wood, and cardboard are poor thermal conductors and would burn or melt.
Q9 Answer: The iron nail dipped in oil will NOT rust because oil creates an impermeable barrier that prevents atmospheric oxygen and water from reaching the nail surface.
Q10 Answer: Physical properties dictate structural and electrical utility (e.g., metallic malleability/ductility for foils and wires; high thermal/electrical conductivity for utensils/circuits; non-metallic electrical resistance for rubber safety gear).
Q11 Answer: No. Sulfur cannot be used because it is a brittle, non-malleable non-metal that cannot form a continuous, durable protective film over iron surfaces.
Q12 Answer: Heating iron until it becomes red-hot weakens its internal lattice structure, making it softer and highly malleable so the ironsmith can beat and shape it into tools easily.

Section 3: Objective Bank Answer Key

MCQs

Q1. C) Phawra
Q2. B) Metallic Lustre
Q3. B) It shatters into small brittle pieces
Q4. B) Sodium and Potassium
Q5. C) Mercury
Q6. C) 2 kilometres
Q7. A) Iron metal and Carbon non-metal
Q8. B) Veena and Sitar
Q9. C) Wood is a poor conductor of heat
Q10. D) Copper wire

Q11. B) To absorb moisture and keep air dry
Q12. C) To expel dissolved gases and block atmospheric air
Q13. B) Hydrated Iron Oxide / Rust (Brown)
Q14. B) Galvanisation
Q15. B) 8 metres tall, over 6000 kilograms
Q16. B) Dazzling white flame forming Magnesium Oxide ash
Q17. B) Red litmus turns Blue
Q18. B) It reacts vigorously with oxygen and water, generating intense heat
Q19. B) Sulfurous acid
Q20. B) Blue litmus paper turns Red

Q21. B) It catches fire spontaneously when exposed to atmospheric air
Q22. D) 118
Q23. C) Iodine
Q24. B) Titanium and Zirconium

Fill-in-the-Blanks

Malleability
Gold
Silver
Brittle
Ductility
Sonority
Conductors
Poor
Rust
Corrosion
Chandragupta II
Basic
Acidic
Water
Element

True/False Questions

False [F]. Corrected: Mercury is a liquid metal at room temperature; sodium and potassium are soft solid metals.
False [F]. Corrected: Wood is neither malleable nor brittle; it does not flatten into sheets when hammered.
False [F]. Corrected: Coal and sulfur are non-ductile and shatter when drawn or hammered.
True [T].
False [F]. Corrected: Iron nails require both dry air (oxygen) and water (moisture) to rust.
False [F]. Corrected: Silver objects develop a black coating, whereas copper develops a green coating.
True [T].
False [F]. Corrected: Non-metal oxides dissolve in water to form acidic solutions that turn blue litmus paper red.
False [F]. Corrected: Plastic, glass, rubber, and paper are not elements, so they are not classified as metallic or non-metallic elements.
True [T].

Section 4: Subjective & Competency Marking Rubrics

Short-Answer Questions

Q1 Rubric:
- Keywords: Red-hot heating, softens iron lattice, increases malleability, easy shaping into tools.
- Section: 4.1 Properties of Materials / Activity 4.1.
Q2 Rubric:
- Keywords: Beaten into ultra-thin sheets; aluminium foil for food wrapping; silver foil for sweet garnishing.
- Section: 4.1.1 Malleability.
Q3 Rubric:
- Keywords: High ductility (drawn into fine wires), excellent electrical conductors, low electrical resistance.
- Section: 4.1.2 Ductility & 4.1.5 Conduction of Electricity.
Q4 Rubric:
- Keywords: Sonority, metallic resonant ringing sound vs dull flat sound of non-metals/wood.
- Section: 4.1.3 Sonority.
Q5 Rubric:
- Keywords: Metal body conducts heat efficiently to food; wooden/plastic handles are poor conductors (insulators) preventing hand burns.
- Section: 4.1.4 Conduction of Heat.
Q6 Rubric:
- Keywords: Hygroscopic agent, absorbs atmospheric moisture, creates completely dry air environment, halts rust reaction.
- Section: 4.2 Effect of Air and Water on Metals (Activity 4.5).
Q7 Rubric:
- Keywords: Boiling expels dissolved oxygen/gases; oil layer forms an impermeable barrier blocking atmospheric air entry.
- Section: 4.2 Effect of Air and Water on Metals (Activity 4.5).
Q8 Rubric:
- Keywords: Extreme reactivity with oxygen and water, highly exothermic reaction, generating severe heat/fire hazard; kerosene acts as protective liquid barrier.
- Section: 4.3 Effect of Air and Water on Other Metals.
Q9 Rubric:
- Keywords: Deflagrating spoon combustion, forms $\text{SO}_2$ gas, dissolves in water forming sulfurous acid ($\text{H}_2\text{SO}_3$), turns blue litmus red.
- Section: 4.4 Substances that Behave Differently (Activity 4.7).
Q10 Rubric:
- Keywords: Definition of element (pure substance non-decomposable chemically); these materials are complex chemical compounds/mixtures, not fundamental elements.
- Section: 4.4 Substances that Behave Differently.

Scenario-Based / Competency Questions

Q1 Rubric:
- Conductors identified: Metal screwdriver shaft, copper power line wire.
- Insulators identified: Plastic screwdriver handle, rubber gloves, rubber shoes, wooden platform.
- Competency explanation: Rubber, plastic, and dry wood prevent electrical current flow, insulating the electrician from electric shocks.
- Section: 4.1.5 Conduction of Electricity.
Q2 Rubric:
- Iron anchor diagnosis: Rusting / Hydrated Iron Oxide formation requiring moist air (oxygen + water).
- Copper statue diagnosis: Surface corrosion forming a basic green copper carbonate film due to atmospheric gas interaction.
- Protective measures: Paint/grease coating or galvanisation for iron; protective sealant for copper.
- Section: 4.2 Effect of Air and Water on Metals.
Q3 Rubric:
- Sodium hazard: Absorbs air moisture, reacts explosively, generates extreme heat and fire.
- Phosphorus hazard: Undergoes spontaneous combustion upon exposure to atmospheric air.
- Storage protocols: Store sodium submerged in kerosene; store elemental phosphorus submerged under water.
- Section: 4.3 & 4.4 Air and Water Effects on Elements.
Q4 Rubric:
- Field A explanation: Burning plant matter yields metallic oxide ash (e.g., Magnesium/Potassium oxide), forming a basic soil solution.
- Field B explanation: Nitrogen and sulfur derivatives form acidic non-metallic compounds (e.g., sulfurous acid derivatives) influencing soil pH.
- Section: 4.3, 4.4 & 4.5 Chemical Nature of Oxides & Uses.
Q5 Rubric:
- Aerospace choice: Titanium (high strength, lightweight, thermal resistance).
- Cable choice: Steel wire cables (alloy of iron metal + carbon non-metal) providing extraordinary tensile strength.
- Section: 4.1.2 & Science and Society.

Long-Answer / Essay Questions

Q1 Rubric:
- Apparatus: Three clean glass bottles (A, B, C), three scrubbed iron nails, silica gel, boiled/cooled water, surface oil, thread.
- Conditions: Bottle A (Dry Air only); Bottle B (Water without Air); Bottle C (Air + Water).
- Result: Nails in A and B remain rust-free after 8–10 days; nail in C develops flaky brown rust.
- Conclusion: Both oxygen and water vapor are essential environmental prerequisites for rusting.
- Section: 4.2 Activity 4.5.
Q2 Rubric:
- Systematic comparison across 7 physical parameters.
- Mentions all major exceptions: Sodium/Potassium (soft metals), Mercury (liquid metal), Coal/Sulfur (brittle non-metals), Wood (neither malleable nor brittle).
- Section: 4.1 Properties of Materials & In a Nutshell.
Q3 Rubric:
- Procedure 1: Magnesium ribbon cleaned with sandpaper, ignited over spirit lamp $\rightarrow$ dazzling white flame $\rightarrow$ white powder ($\text{MgO}$) $\rightarrow$ dissolved in warm water $\rightarrow$ turns red litmus paper blue (Basic oxide).
- Procedure 2: Sulfur powder burned in deflagrating spoon inside sealed gas jar $\rightarrow$ $\text{SO}_2$ gas formed $\rightarrow$ dissolved in water $\rightarrow$ sulfurous acid ($\text{H}_2\text{SO}_3$) $\rightarrow$ turns blue litmus paper red (Acidic oxide).
- Reaction Word Equations provided for both metals and non-metals.
- Section: 4.3 Activity 4.6 & 4.4 Activity 4.7.
Q4 Rubric:
- Harappan Era: Proficiency in copper and gold craftwork; lack of iron usage.
- Agricultural Transformation: Iron ploughs, axes, and spades revolutionised farming efficiency and civilisational growth.
- Chandragupta II Era: Engineering details of Iron Pillar of Delhi (8m height, >6000 kg weight, >1600 years rust resistance).
- Modern Era: Industrial recycling of iron and aluminium in India for waste reduction and sustainability.
- Section: Holistic Lens, Fascinating Facts & Science and Society.
Q5 Rubric:
- Oxygen: Essential for cellular respiration in living organisms.
- Carbon: Fundamental building block of life; present in proteins, carbohydrates, and fats.
- Nitrogen: Essential nutrient for plant growth; key component in agricultural fertilizers.
- Chlorine: Primary agent in municipal water purification systems.
- Iodine: Applied as antiseptic solution on wounds and cuts.
- Phosphorus: Crucial reactive non-metal stored underwater.
- Section: 4.4 & 4.5 Essential Uses of Non-metals.