Class 7 Science · Chapter 4
Short answer: Class 7 Science "Curiosity" book ka Chapter 4 hai "The World of Metals and Non-Metals" — metals aur non-metals ki physical properties (lustre, malleability, ductility, conductivity, sonority) compare karta hai, plus kuch chemical reactions (acid ke saath, oxygen ke saath) cover karta hai. Yeh chapter Class 8-10 tak chalne wali metallurgy aur reactivity series ki neev hai.
Class 7 Science ki Curiosity book (2026-27 rationalised syllabus, 12 chapters) ka Chapter 4 — "The World of Metals and Non-Metals" — humein rozmarra ki cheezon ko do bade groups mein baantna sikhata hai: metals aur non-metals. Yeh koi naya topic nahi hai — aap already jaante ho ki iron (loha) hard hota hai aur sulphur powder jaisa crumbly. Lekin yeh chapter in observations ko systematic properties mein convert karta hai: lustre (chamak), malleability (peetne se sheet banna), ductility (khinch kar wire banna), conductivity (heat aur electricity pass karna), aur sonority (dhwani/ringing sound).
Is chapter ka scope sirf physical properties tak nahi rukta — thodi chemical reactivity bhi cover hoti hai: metals ka acid ke saath react karke hydrogen gas banana, aur kuch metals ka oxygen ke saath jal kar oxide banana. Curiosity book mein pichli 13-chapter edition ke standalone chapters jaise "Acids, Bases and Salts" ab is book mein reduced/merged form mein aate hain, isliye topic weightage thoda alag feel hoga agar aapne purani book dekhi hai.
Chapter 1 poore Class 10 Chemistry ki neev hai — waise hi yeh Chapter 4 poore secondary school ki metallurgy (Class 10 "Metals and Non-Metals") aur reactivity series ki neev hai. Agar yahan properties clear ho gayi, toh aage activity series, ores, aur extraction of metals samajhna easy ho jayega.
Chapter 4 Summary — 5 Minute Revision
Chapter 4 metals aur non-metals ko unki physical aur chemical properties ke through classify karta hai. Metals — jaise iron, copper, aluminium, gold — generally lustrous (chamakdaar), malleable (haturi se peet kar sheet ban jaate hain), ductile (khinch kar tar ban jaate hain), sonorous (dhwani karte hain jab peeta jaaye), aur good conductors of heat and electricity hote hain. Exceptions bhi yaad rakhne zaroori hain: mercury room temperature par liquid metal hai, aur sodium/potassium itne soft hote hain ki knife se kaate ja sakte hain.
Non-metals — jaise sulphur, carbon, oxygen, phosphorus — generally non-lustrous (dull), brittle (peetne se toot jaate hain), non-ductile, poor conductors (except graphite, jo carbon ka form hai aur electricity conduct karta hai), aur non-sonorous hote hain. Iodine ek exception hai jisme lustre dikhta hai.
Chemical properties mein, metals dilute acids ke saath react karke hydrogen gas release karte hain aur corresponding salt banate hain — jaise zinc + dilute sulphuric acid → zinc sulphate + hydrogen. Metals oxygen ke saath jal kar basic oxides banate hain (jaise magnesium oxide), jabki non-metals oxygen ke saath react karke acidic ya neutral oxides banate hain (jaise sulphur dioxide, jo paani mein ghulne par acid banata hai). Yeh chapter humein sikhata hai ki materials ki everyday behaviour — bijli ka taar copper ka kyun banta hai, jewellery gold/silver ki kyun banti hai — inn hi fundamental properties se nikalti hai.
In-Text Questions — Solutions
Sabhi metals room temperature par solid hote hain — kya yeh statement sahi hai? Reason do.
Nahi, yeh statement galat hai. Mercury (Hg) ek exception hai jo room temperature par liquid state mein paaya jaata hai, jabki baaki lagbhag saare metals solid hote hain. Isliye 'sabhi metals solid hote hain' generalize karna sahi nahi hai — thermometers aur barometers mein mercury isi liquid property ki wajah se use hota hai.Ek student ne kaha 'graphite ek non-metal hai isliye yeh electricity conduct nahi karega.' Kya yeh sahi hai?
Nahi, yeh galat hai. Graphite carbon ka ek allotrope (form) hai aur non-metal hone ke bawajood yeh electricity conduct karta hai — yeh non-metals mein ek important exception hai. Isi property ki wajah se graphite ko electrodes (dry cells, electrolysis) mein use kiya jaata hai.Sodium ko chaaku se kaata jaa sakta hai. Iska metals ki general property se kya conflict hai aur kyun?
Metals generally hard hote hain, lekin sodium aur potassium jaise alkali metals apwaad (exception) hain — yeh itne soft hote hain ki chaaku se aasani se kaate ja sakte hain. Yeh unki weak metallic bonding ki wajah se hota hai. Isi wajah se sodium ko safety ke liye kerosene oil mein store kiya jaata hai taaki yeh air/moisture ke sampark mein na aaye.Exercise Questions — Solutions (Q1–Q5)
Metals aur non-metals ke beech physical properties ke aadhar par kaam se kaam char (4) differences likho.
| Property | Metals | Non-metals |
|---|---|---|
| Lustre | Lustrous (chamakdaar) — polish karne par shine karte hain | Non-lustrous (dull), except iodine |
| Malleability | Malleable — haturi se peet kar sheet bana sakte hain | Non-malleable — peetne par powder ya tukde ban jaate hain (brittle) |
| Ductility | Ductile — khinch kar tar (wire) bana sakte hain | Non-ductile |
| Conductivity | Heat aur electricity ke good conductors | Poor conductors, except graphite |
↔ Table ko side me swipe karein
Zinc granules ko dilute hydrochloric acid mein daala gaya. (a) Kya reaction hoga? (b) Balanced word equation likho. (c) Gas ki pehchan kaise karoge?
(a) Zinc metal, dilute hydrochloric acid ke saath react karke zinc chloride salt aur hydrogen gas banayega. Bubbles nikalte hue dikhenge.
Zinc + Dilute Hydrochloric acid → Zinc chloride + Hydrogen gas
Zn + 2HCl → ZnCl2 + H2↑
(c) Nikalne wali gas ko test tube ke mooh par jalti hui matchstick le jaakar test karte hain — agar 'pop' sound ke saath jalti hai, toh confirm hota hai ki gas hydrogen hai.
Magnesium ribbon ko air mein jalaya jaata hai. Product ka naam batao aur is oxide ki nature (acidic/basic) bhi batao. Ek chemical equation likho.
Magnesium, oxygen ke saath jal kar magnesium oxide banata hai — yeh reaction bright white light ke saath hoti hai.
2Mg + O2 → 2MgO
Magnesium oxide (MgO) nature mein basic hai — yeh paani mein ghulkar magnesium hydroxide banata hai jo litmus ko blue kar deta hai, is tarah metal oxides generally basic hote hain (kuch amphoteric bhi ho sakte hain jaise aluminium oxide).
Sulphur ko jalaya jaata hai aur uski gas paani mein pass ki jaati hai. Litmus paper se result kya expect karoge aur kyun?
Sulphur, oxygen mein jal kar sulphur dioxide gas banata hai.
S + O2 → SO2
Jab SO2 ko paani mein pass karte hain, yeh sulphurous acid banata hai jo blue litmus paper ko red kar deta hai. Yeh dikhata hai ki non-metal oxides generally acidic nature ke hote hain — metal oxides (basic) ke bilkul opposite behaviour.
Ek unknown solid X hai jo hammer se peetne par toot jaata hai aur electricity conduct nahi karta, lekin dull-looking bhi nahi hai. Kya X metal hai ya non-metal? Apna reasoning do.
X ek non-metal hoga, lekin yeh iodine jaisa exception ho sakta hai. Reasoning: brittleness (toot jaana) aur non-conductivity dono non-metal ki classic properties hain — yeh strongly non-metal ki taraf point karte hain. Lustre hona thoda confusing lag sakta hai, lekin iodine ek non-metal hai jo phir bhi lustrous (shiny) hota hai — isliye X, iodine jaisa koi exception element ho sakta hai, sirf lustre dekh kar use metal nahi keh sakte.Important Equations — Ek Nazar Me
| Concept | Rule / Equation |
|---|---|
| Metal + Dilute Acid | Metal + Dilute Acid → Salt + Hydrogen gas (H2) |
| Zinc + HCl | Zn + 2HCl → ZnCl2 + H2↑ |
| Metal + Oxygen | Metal + O2 → Basic Oxide |
| Magnesium burning | 2Mg + O2 → 2MgO |
| Non-metal + Oxygen | Non-metal + O2 → Acidic/Neutral Oxide |
| Sulphur burning | S + O2 → SO2 |
| Hydrogen gas test | Jalti matchstick se 'pop' sound → H2 confirm |
↔ Table ko side me swipe karein
Common Mistakes — Yahan Marks Kat te Hain
- Yeh soch lena ki 'sabhi metals solid hote hain' — mercury exception ko bhool jaana, jo room temperature par liquid hai.
- Graphite ko metal samajh lena kyunki yeh electricity conduct karta hai — yaad rakho graphite carbon ka non-metal form hai, sirf conductivity mein exception hai.
- Iodine ko uski chamak (lustre) dekh kar metal maan lena — iodine non-metal hai, lekin lustrous exception hai.
- Metal oxide aur non-metal oxide ki acidic/basic nature ulta likh dena — metal oxides basic hote hain, non-metal oxides acidic hote hain, yeh confuse mat karo.
- Balanced equation likhte waqt H2, O2 jaise molecules ke subscripts bhool jaana ya coefficients balance na karna.
- Sodium/potassium ko unki softness dekh kar non-metal samajh lena — softness sirf ek exception hai, yeh phir bhi reactive metals hain jo kerosene mein store hote hain.
Board-Style Important Questions
- Class 7 board-level formal PYQs available nahi hain kyunki yeh non-board internal-assessment class hai — school ke periodic tests aur unit tests mein iss chapter se questions aate hain.
- School unit tests mein commonly poocha jaane wala pattern: 'Metals aur non-metals mein char differences do' — yeh iss chapter ka sabse frequent question type hai.
- Diagram-based questions: metal ki malleability/ductility dikhane wale labelled diagrams banane ko kaha jaata hai.
- Practical-based question: 'Zinc granules + dilute acid' activity ke observations aur equation likhna — yeh lab-manual se directly aata hai.
- HOTS (Higher Order Thinking) type: exceptions (mercury, sodium, graphite, iodine) par based reasoning questions school assessments mein common hain.
Aksar Poochhe Jaane Wale Sawaal
Class 7 Science Curiosity book mein total kitne chapters hain 2026-27 session ke liye?
2026-27 rationalised session ke liye current NCERT Class 7 Science 'Curiosity' book mein 12 chapters hain — yeh purani 13-chapter book se reduced hai. Purani book ke kai chapters jaise Nutrition in Plants, Nutrition in Animals, Respiration, Acids-Bases-Salts (standalone), Motion and Time, Electric Current and its Effects rationalise ho chuke hain ya merge ho gaye hain, isliye agar aap purane aggregator sites dekh rahe ho toh chapter list match nahi karegi.
World of Metals and Non-Metals chapter ka NCERT class 7 science curiosity chapter number kya hai?
Yeh Chapter 4 hai Curiosity book mein. Chapter order verify karne ke liye multiple independent sources cross-check kiye gaye hain, lekin final confirmation ke liye ncert.nic.in ki official PDF dekhna recommended hai, kyunki hum directly primary source access nahi kar paaye.
Class 7 mein metal aur non-metal ki sabse important property kya hai jo exam mein zyada poochi jaati hai?
Malleability aur ductility metals ki sabse distinctive properties hain jo non-metals mein absent hoti hain — yeh differentiation ka core basis hai aur exams/tests mein sabse zyada poocha jaata hai. Conductivity bhi close second hai kyunki iska real-life application (electrical wires) directly connect hota hai.
Kya iss chapter mein Acids, Bases aur Salts detail mein cover hoti hain jaise purani book mein thi?
Nahi, purani 13-chapter NCERT book mein 'Acids, Bases and Salts' ek standalone chapter tha jo rationalise ho chuka hai. Current Curiosity book ke Chapter 4 mein sirf itna cover hota hai ki metals dilute acids ke saath react karke hydrogen gas banate hain — pura acid-base-salt classification is chapter ka scope nahi hai. Agar aap 'exploring substances acidic basic neutral class 7 notes' dhoond rahe ho, woh topic kisi doosre chapter mein alag angle se cover hota hai, standalone acid-base chapter ke roop mein nahi.
Metal ka oxide basic hota hai aur non-metal ka oxide acidic — iska real-life example kya hai?
Magnesium oxide (metal oxide) paani mein ghulkar basic solution banata hai jo antacid tablets mein use hota hai. Sulphur dioxide (non-metal oxide) paani mein ghulkar acidic solution banata hai, aur yeh hi gas industrial pollution se acid rain ka ek karan bhi banti hai — is real-world connection se students ko concept yaad rakhna easy hota hai.
Class 7 Science ke doosre chapters — jaise Electricity Circuits, Heat Transfer, Light Shadows and Reflections — inn topics ka is chapter se koi connection hai?
Directly nahi, lekin conceptually haan — 'electricity circuits and their components class 7' chapter mein jab conductors/insulators padhte ho, tab wahi metals (jo good conductors hain) is Chapter 4 se connect ho jaate hain. Isi tarah 'heat transfer in nature' chapter mein bhi metals ki thermal conductivity property yahan se link hoti hai. Yeh chapters independent hain lekin underlying properties overlap karti hain.
Class 7 Science — Saare Chapters
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