NCERT Solutions Class 7 Science Chapter 4: The World of Metals and Non-metals (Hinglish)

Curiosity, Class 7 Science ki kitaab (Reprint 2026-27) ke Chapter 4, The World of Metals and Non-metals, ke har sawaal ke jawab: text ke sawaal, Table 4.1 se 4.3 ke saath Activity 4.1 se 4.8, Holistic Lens aur Dive Deeper boxes, Let Us Enhance Our Learning ke baarah sawaal aur Exploratory Projects. Page numbers kitaab ke hisaab se hain (pages 41–56). Activities ke jawab ummeed ke nateeje batate hain; apne observations khud likho. Chhote notes: Chapter 4 ke notes.

Lohaar ke paas (pages 41–42)

Kya doosre metals bhi peetkar chapte kiye ja sakte hain? Haan. Zyaadatar metals malleable hain: copper, aluminium, gold aur chaandi sab peetkar patli chaadar ban sakte hain, jaise aluminium foil aur mithaai pe chaandi ka warq. Iron ko pehle garam karte hain kyunki laal garam iron naram aur aakaar dene mein aasaan hota hai.

Activity 4.1 aur Table 4.1 (pages 42–44)

Table 4.1: roop, sakhti aur peetne ka asar (list ki tarah):

• Copper ka tukda: chamakdaar; sakht; chapta ho jaata hai.
• Aluminium ka tukda: chamakdaar; sakht; chapta ho jaata hai.
• Iron ki keel: chamakdaar; sakht; chapti ho jaati hai.
• Coal ka tukda: dhundhla; metals jitna sakht nahi; tukdon mein toot jaata hai.
• Sulfur ka dala (matar jitna): dhundhla; naram; tukdon mein toot jaata hai.
• Lakdi ka gutka: dhundhla; metals jitna sakht nahi; na chapta hota hai na toot-ta hai.

Kaunsi cheezein chamakdaar aur sakht hain? Kaunsi chapti hoti hain? Copper, aluminium aur iron chamakdaar aur sakht hain, aur peetne pe chapte hote hain: ye metals hain, aur malleable hain. Coal aur sulfur bhurbhure hain, aur lakdi na malleable hai na bhurbhuri.

Metal ki chaadaron ke udaaharan. Khaana lapetne ki aluminium foil, kuch mithaiyon pe chaandi ka patla warq, chhat aur sandook ke liye tin ya steel ki chaadarein, aur bartano ke liye copper ki chaadar.

Holistic Lens (page 44)

Kyun maana jaata hai ki copper iron se pehle khoja gaya? Copper kabhi-kabhi prakriti mein shuddh metal ki tarah milta hai, aur ise ores se kam taapmaan pe nikaala ja sakta hai, isliye puraane log saadhaaran aag se ise dhoondh aur dhaal sakte the. Iron lagbhag kabhi shuddh nahi milta, aur ise ores se nikaalne ke liye kahin zyaada garam bhattiyan chahiye, jinhe banne mein lamba samay laga. Isiliye Harappa ke log copper aur gold use karte the par iron lagbhag nahi.

Ductility (pages 44–45)

Metal ke taar kahan use hote hain? Bijli ki fittings aur cables mein copper aur aluminium ke taar, kangan, haar aur jhumke, veena, sitar, violin ya guitar ke taar, chai ki chhanni ki jaali, aur jhoolte pulon aur cranes mein steel ki rassiyan.

Activity 4.2: Sonority (pages 45–46)

Kya aawaaz mein farq hai? Haan. Metal ka chammach aur sikka khanakti aawaaz dete hain, jabki coal ka tukda aur lakdi ka gutka dhap ki aawaaz. Metals sonorous hain.

Activity 4.3: Garmi ka conduction (pages 46–47)

Khaana pakaane ke bartan kin metals ke hote hain, aur kyun? Aluminium, copper, iron aur stainless steel (jo zyaadatar iron hai). Ye garmi achhe se guzaarte hain, isliye khaana barabar pakta hai, aur ye mazboot hain aur chulhe pe pighalte nahi.

Kaunsa chammach zyaada garam hota hai? Isse kya pata chalta hai? Metal ka chammach. Garmi garam paani se metal ke chammach ke upar tak pahunchti hai, par lakdi ke chammach mein lagbhag nahi. Metals garmi ke achhe conductors hain, aur lakdi kharaab conductor hai.

Activity 4.4 aur Table 4.2 (pages 47–48)

Screwdriver ka handle kis cheez ka hota hai, aur electrician rubber ke dastaane aur joote kyun pehente hain? Handle plastic ka hota hai, aur dastaane aur joote rubber ke. Plastic aur rubber bijli ke kharaab conductors hain, isliye ye electrician ko current ke jhatke se bachaate hain.

Table 4.2: bijli ka conduction (list ki tarah):

• Aluminium foil: bulb jalta hai; achha conductor.
• Iron ki keel: bulb jalta hai; achha conductor.
• Sulfur ka dala: nahi jalta; kharaab conductor.
• Copper ka taar: bulb jalta hai; achha conductor.
• Coal ka tukda: nahi jalta; kharaab conductor.
• Sookhi lakdi: nahi jalta; kharaab conductor.
• Patthar: nahi jalta; kharaab conductor.
• Rubber ka eraser: nahi jalta; kharaab conductor.
• Nylon ki rassi: nahi jalta; kharaab conductor.

Kya koi pattern hai? Haan: bulb jalaane waala har padaarth metal hai.

Activity 4.5 aur Table 4.3 (pages 48–50)

Kin shartoon mein iron pe bhoori parat aati hai? Sirf tab jab use hawa aur paani dono milein.

Table 4.3 (list ki tarah):

• Bottle A: paani, nahi; hawa, haan; bhoori parat nahi.
• Bottle B: paani, haan; hawa, nahi; bhoori parat nahi.
• Bottle C: paani, haan; hawa, haan; keel pe bhoori parat (jang).

Kya nishkarsh nikalta hai? Sirf sookhi hawa (A) aur sirf paani (B) se iron ko jang nahi lagta; hawa aur paani dono saath (C), yaani nam hawa, chahiye.

Doosre metals pe parat. Copper ki cheezon pe hari parat aur chaandi ki cheezon pe kaali parat corrosion hai, yaani hawa, paani ya doosre padaarthon se metals ka dheere-dheere kharaab hona.

Activity 4.6: Magnesium jalaana (page 51)

Kya dikhta hai? Ribbon chaundhiya dene waali safed lau se jalta hai aur safed powder, magnesium oxide, ban jaata hai.

Iska ghol acidic, basic ya neutral hai? Litmus pe kya asar hai? Ye laal litmus paper ko neela karta hai aur neele ko neela hi rehne deta hai, isliye ye basic hai.

Sodium ke oxide ki prakriti ka andaaza (page 52). Basic, kyunki sodium metal hai aur metals ke oxides aam taur pe basic hote hain.

Activity 4.7 aur 4.8: Sulfur (pages 52–53)

Jale sulfur se bane ghol ki jaanch mein kya dikhta hai? Ye neele litmus paper ko laal karta hai, isliye ye acidic hai: sulfur jalkar sulfur dioxide banaata hai, jo paani mein ghulkar sulfurous acid banaati hai.

Kya sulfur paani mein metals jaisa vyavhaar karta hai? Nahi. Paani mein daala sulfur powder koi reaction nahi dikhata.

Oxygen ke upyog (page 54)

Oxygen ke aur upyog. Aspataalon mein mareezon ke liye, aur parvataarohiyon aur gotakhoron ke liye oxygen cylinder; chulhon aur engine mein eendhan jalne ke liye ye zaroori hai; aur machhliyan aur paani ke doosre jeev paani mein ghuli oxygen lete hain.

Let Us Enhance Our Learning (pages 55–56)

1. (i) Aluminium. Ye sasta hai, aur iski patli chaadarein kisi bhi aakaar mein aasaani se mud jaati hain.

2. (iv) Sodium. Ye paani se tez reaction karta hai aur itni garmi deta hai ki aag pakad sakta hai; isiliye ise kerosene mein rakhte hain.

3. Sahi ya galat, kaaran ke saath.

• (i) Galat. Aluminium aur copper metals hain, non-metals nahi.
• (ii) Galat. Metal oxides basic hote hain, isliye unke ghol laal litmus ko neela karte hain; neele litmus ko laal karna acidic ghol ka kaam hai.
• (iii) Sahi. Oxygen non-metal hai, aur saans lene (respiration) ke liye zaroori hai.
• (iv) Galat. Copper ke bartan paani ubaalne ke liye isliye use hote hain kyunki copper garmi ka achha conductor hai, bijli ka conductor hone ki vajah se nahi.

4. Gehne banaane ke liye kuch hi metals kyun theek hain? Gehno ko saalon chamakdaar rehna chahiye, baareek design mein dhalna chahiye aur twacha pe surakshit hona chahiye. Gold, chaandi aur platinum chamakdaar, bahut malleable aur ductile hain, aur hawa aur paani se lagbhag reaction nahi karte, isliye unki chamak bani rehti hai (chaandi dheere-dheere kaali padti hai aur polish maangti hai). Zyaadatar doosre metals corrode hote hain, jaise iron ko jang lagta hai ya copper hara padta hai, aur sodium jaise kuch khatarnaak reaction karte hain. Keemti metals durlabh aur mulyavaan bhi hain.

5. Upyogon ko suljhaaye naamon se milaana.

• (i) Bijli ki wiring mein: (c) PEPORC = COPPER
• (ii) Sabse zyaada malleable aur ductile: (e) OGDL = GOLD
• (iii) Jiske bina jeev jee nahi sakte: (a) ENXYGO = OXYGEN
• (iv) Jis waali khaad se paudhe swasth badhte hain: (d) TENGOINR = NITROGEN
• (v) Paani saaf karne mein: (b) NECOHIRL = CHLORINE

6. Magnesium aur sulfur ke saath oxygen. Magnesium oxygen mein chaundhiya dene waali safed lau se jalkar magnesium oxide, safed powder, banaata hai; paani mein iska ghol basic hai aur laal litmus ko neela karta hai. Sulfur oxygen mein jalkar sulfur dioxide, ek gas, banaata hai; paani mein ghulkar ye sulfurous acid banaati hai, jo acidic hai aur neele litmus ko laal karti hai. Yaani metal thos, basic oxide aur non-metal gas jaisa, acidic oxide banaata hai.

7. Poora flow chart. Magnesium + hawa + garmi → raakh (magnesium oxide) → paani ke saath → basic ghol → neela aur laal litmus ghol alag-alag milaao → neela litmus: koi badlaav nahi, neela hi rehta hai; laal litmus: neela ho jaata hai.

8. Paani ubaalne ke pan ke liye padaarth. Copper, aur doosri pasand iron. Pan ko garmi achhe se guzaarni chahiye, mazboot hona chahiye, peetkar aakaar mein dhalna chahiye aur lau pe na pighalna chahiye na jalna. Copper malleable hai aur garmi bahut achhe se guzaarta hai, isliye paani jaldi ubalta hai. Iron bhi chalega, par wo bhaari hai, dheere garam hota hai aur use jang lagta hai. Sulfur aur coal bhurbhure aur kharaab conductors hain; plastic pighal jaata hai; lakdi aur gatta aag pakad lete hain aur garmi kharaab guzaarte hain.

9. Tel, paani aur sirke mein keelein. Tel mein doobi keel ko jang nahi lagega, kyunki tel hawa aur paani dono ko iron se door rakhta hai. Paani waali keel ko jang lagega, kyunki paani mein hawa ghuli hoti hai, aur sirke waali ko bhi, kyunki sirka zyaadatar paani hai aur acidic hai.

10. Gun upyog kaise tay karte hain.

• Malleable metals se foil, chaadar aur bartan bante hain; ductile metals se taar.
• Metals garmi guzaarte hain, isliye bartan metal ke hote hain; bijli guzaarte hain, isliye taar copper ya aluminium ke.
• Sonorous metals se ghanti aur ghungroo, chamakdaar gold aur chaandi se gehne, aur mazboot iron aur steel se auzaar, pul aur cranes bante hain.
• Non-metals apne kaam ke liye use hote hain: saans ke liye oxygen, har jeev mein carbon, khaad mein nitrogen, paani saaf karne ke liye chlorine aur antiseptic iodine.

11. Kya iron pe zinc ki jagah sulfur ki parat chadh sakti hai? Nahi. Zinc ek metal hai jo iron pe chipakne waali patli, mazboot parat ki tarah phailaaya ja sakta hai. Sulfur bhurbhura aur powder jaisa hai aur malleable nahi, isliye ye mazboot, bina toote parat nahi bana sakta; ye chatakkar gir jaayega aur nam hawa iron tak pahunch jaayegi. Sulfur ko jalaane ya garam karne pe sulfur dioxide bhi banti hai, ek nuksaandeh gas jo nami ke saath acid banaati hai.

12. Lohaar auzaar banaane se pehle iron ko garam kyun karta hai? Garam karne se iron laal garam aur kaafi naram ho jaata hai, isliye use bina chatke aasaani se peetkar aakaar diya ja sakta hai. Thanda iron sakht hota hai aur kulhaadi ya phawde ke aakaar mein nahi mudega.

Exploratory Projects (page 56)

Bharat ki dhaatu kala. Dhokra (peetal ki dhalaai) Chhattisgarh, West Bengal, Odisha, Jharkhand aur Madhya Pradesh mein banti hai; Bidriware, kaale metal pe chaandi ki jadaai, Bidar, Karnataka mein; Pembarthi peetal ka kaam Telangana mein; aur Kamrupi kaanse aur peetal ka kaam Assam mein. Inki tasveeron ka collage banao.

Bharat mein dhaatu ke ores kahan milte hain. Iron ore: Odisha, Chhattisgarh, Jharkhand, Karnataka aur Goa; gold: Karnataka; bauxite, yaani aluminium ka ore: Odisha, Jharkhand, Chhattisgarh aur Gujarat; copper: Rajasthan, Jharkhand aur Madhya Pradesh. Inhe atlas se liye Bharat ke outline map pe dikhao.

Smartphone mein metals aur non-metals. Copper ki wiring current le jaati hai, contacts pe gold ki parat hoti hai kyunki wo corrode nahi hota, aluminium se halka frame banta hai, battery mein lithium aur cobalt hote hain, hisse jodne mein tin lagta hai, aur silicon ke chips computing karte hain. Kaanch ki screen aur plastic ka case elements nahi hain.

Debate: aaraam aur vilaasita ke liye zyaada ya kam metals? Zyaada ke paksh mein: metals mazboot, tikaau aur recycle hone waale saamaan banaate hain, aur aaj ke jeevan ko inki zaroorat hai. Kam ke paksh mein: khanan jangal aur zameen bigaadta hai, metals nikaalne mein bahut energy aur pradooshan hota hai, aur ores khatam ho jaayenge. Santulit raay: jahan zaroori ho wahan metals use karo, unhe recycle karo aur barbaadi se bacho.

Chhote notes aur aur practice topic pages pe hain: metals aur non-metals ki properties, metals mein jang kyun lagta hai aur metal aur non-metal oxides.