Paani mein Ghuli Gases
Paani mein hawa bhi ghuli hoti hai? Haan! Aur isi se machhliyaan saans leti hain. 🐟
🧭 Is Post Mein
📖 Kahani: Glass ke Andar Chhote-Chhote Moti
Sunday ki dopahar thi. Golu ne subah fridge se thande paani ka glass nikaal kar khidki ke paas rakh diya tha aur bhool gaya. Dopahar ko dekha toh glass ki andar ki deewar par chhote-chhote chamakte bulbule chipke the, jaise kisi ne moti chipka diye hon! “Maine toh isme soda nahi daala tha. Yeh bulbule aaye kahan se?”
Paas mein Priya apne goldfish ke bowl ki safai kar rahi thi. Usne kaha: “Pata hai, papa ne bola hai ki machhli ke bowl mein kabhi ubla hua paani thanda karke mat daalna. Machhli pareshaan ho jaayegi. Par kyun? Paani toh saaf hi hai!”
Rohan ne apni soda ki bottle kholi, “psssh!” ki aawaaz aayi aur bulbule upar bhaage. Woh hansa: “Bulbule toh bas soda mein hote hain. Saada paani mein hawa kahan se aayegi? Aur machhli toh paani ke H₂O wale oxygen se saans leti hai!”
Toh sawaal yeh hain: kya saada paani mein bhi gases ghuli hoti hain? Machhli asal mein kaunsi oxygen leti hai? Aur garmi mein gases ka kya hota hai? Aaj inka jawaab dhoondhte hain. 🔍
🎯 Is Post Mein Kya Seekhenge
- Gases bhi paani mein ghulti hain, jaise oxygen, carbon dioxide aur nitrogen
- Paani mein ghuli oxygen (dissolved oxygen) bahut thodi hoti hai, phir bhi poora jaliya jeevan isi par tika hai
- Gas ka paani mein ghol ek uniform mixture yaani solution hai
- Taapmaan badhne par gases ki solubility ghatti hai (solids ka ulta!)
- Soda ki bottle aur dabaav (pressure) ka gas ke ghulne se rishta
- Garam paani, ubla paani aur machhliyon ki pareshani: asli zindagi ke udaharan
🧱 Basics: Pehle Yeh Aana Chahiye
1. Solute, solvent, solution: jo ghulta hai woh solute, jisme ghulta hai woh solvent, aur dono ka uniform mel solution. Solute thos (solid) hi ho, zaroori nahi; woh liquid ya gas bhi ho sakta hai.
2. Solubility: tay matra ke solvent mein, ek taapmaan par, zyada se zyada kitna solute ghul sakta hai.
3. Pichle post ka niyam: zyaadatar solids garam paani mein zyada ghulte hain. Aaj dekhenge ki gases ke liye kahani ulti kyun hai.
4. Hawa ek mixture hai: hawa mein lagbhag 78% nitrogen, 21% oxygen, aur thodi carbon dioxide, argon aur jal-vaashp (water vapour) hoti hai. Yeh gases aapas mein barabar mili hoti hain, isliye hawa bhi ek uniform mixture hai.
💡 Concept: Paani ke Andar Chhupi Hawa
Step 1: Gases bhi solute ban sakti hain. Jab paani hawa ke sampark mein hota hai (nadi, talaab, glass, sab jagah), toh hawa ki kuch gases dheere-dheere paani mein ghul jaati hain. Inme oxygen, nitrogen aur carbon dioxide pramukh hain. Yahan paani solvent hai aur gas solute.
Step 2: Oxygen bahut kam ghulti hai. Oxygen paani mein bas thodi si ghulti hai. 20 °C par 1 litre paani mein lagbhag 9 mg (milligram) oxygen hi ghuli hoti hai. Yaad hai, 100 g paani mein lagbhag 204 g cheeni ghul jaati hai? Usse tulna karo toh oxygen lakhon guna kam ghulti hai!
Step 3: Itni thodi, par bahut zaroori. Yahi thodi si ghuli oxygen, jise dissolved oxygen kehte hain, machhliyon, kekdon, jal-keedon aur paani ke paudhon sabko zinda rakhti hai. Machhliyaan apne galphade (gills) se paani mein ghuli isi oxygen ko kheenchti hain.
Step 4: Yeh ghol uniform hai. Gas paani mein barabar fail jaati hai. Aap ghuli hui oxygen ko aankh ya magnifying glass se alag nahi dekh sakte. Isliye paani mein gas ka mel ek uniform mixture, yaani solution hai.
Step 5: Garmi badhi, gas ghati. Solids ke ulat, gases ki solubility taapmaan badhne par aam taur par ghatti hai. Thande paani mein zyada oxygen ghul sakti hai, garam paani mein kam.
0 °C → 14.6 mg · 10 °C → 11.3 mg · 20 °C → 9.1 mg · 30 °C → 7.6 mg · 40 °C → 6.4 mg
0 °C se 40 °C tak jaate-jaate oxygen ki matra aadhi se bhi kam ho jaati hai.
Step 6: Kyun ghatti hai? Garam karne par paani aur gas, dono ke kan zyada urja (energy) se tez hilne lagte hain. Gas ke halke kan itni urja paakar paani ki pakad se chhoot jaate hain aur bulbule banakar bahar nikal jaate hain. Golu ke glass mein yahi hua: thanda paani dhoop mein garam hua, uski ghuli hawa bahar aane lagi aur deewar par bulbule ban gaye.
Step 7: Dabaav (pressure) bhi kaam karta hai. Soda ki bottle mein carbon dioxide ko zyada dabaav par paani mein ghola jaata hai aur bottle kas kar band ki jaati hai. Jaise hi dhakkan khulta hai, dabaav ghatta hai, gas ki solubility ghatti hai aur gas “psssh!” ke saath bulbule banakar bhaagti hai. Garam soda isliye jaldi “flat” (bina gas ka) ho jaata hai.
Ek line mein: gases paani mein ghulti hain (thodi), ghol uniform hota hai, aur gases ke liye: taapmaan ⬆ = solubility ⬇; dabaav ⬆ = solubility ⬆.
🖼️ Diagrams: Picture se Samjho
🔐 Deep Concept: Paani ki Saans ka Hisaab-Kitaab
1. Oxygen paani mein aati kahan se hai? Do raaston se: (a) hawa se, paani ki satah (surface) par hawa ki oxygen dheere-dheere ghulti rehti hai. Lahrein, jharne aur behti nadi hawa ko paani mein milaati hain, isliye behte paani mein oxygen zyada hoti hai. (b) Paani ke paudhon se, jo din mein photosynthesis karke oxygen chhodte hain.
2. Oxygen jaati kahan hai? Machhliyaan, keede aur paudhe saans lene mein use karte hain. Saath hi paani mein sadta hua kachra (patte, khaana, gandagi) bhi bacteria dwara todte waqt oxygen khaata hai. Isliye ganda paani aksar oxygen ki kami wala hota hai.
3. Garmi ka double vaar: garmi mein (a) paani kam oxygen pakad sakta hai, aur (b) machhliyon ka sharir tez kaam karta hai, unhe zyada oxygen chahiye hoti hai. Kam supply, zyada maang! Isliye garmi ke mausam mein talaabon mein machhliyaan subah-subah satah par aakar munh khol-khol kar saans leti dikhti hain.
4. Dabaav ka niyam: gas par jitna zyada dabaav, utni zyada woh liquid mein ghulti hai. Soda factory mein carbon dioxide ko dabaav daal kar paani mein bhara jaata hai. Ulta, oonche pahadon par hawa ka dabaav kam hota hai, toh wahan ke paani mein thodi kam oxygen ghulti hai.
✏️ Examples: Ghuli Gases Har Jagah
10 °C: 11.3 mg × 1000 = 11,300 mg = 11.3 g
30 °C: 7.6 mg × 1000 = 7,600 mg = 7.6 g
Yaani garmi se 3.7 g oxygen kam! Lagbhag ek-tihaai oxygen chali gayi.
⚖️ Difference Table: Solid Solute vs Gas Solute
| Baat | Solid solute (jaise cheeni) | Gas solute (jaise oxygen) |
|---|---|---|
| Taapmaan badhne par solubility | Aam taur par badhti hai | Aam taur par ghatti hai |
| Garam karne par kya dikhta hai | Neeche bacha solute ghul jaata hai | Bulbule banakar gas bahar nikalti hai |
| Thanda karne par | Extra solute crystals ban kar bahar | Zyada gas ghul sakti hai |
| Dabaav (pressure) ka asar | Lagbhag nahi | Dabaav badhe toh zyada ghulti hai |
| Kitna ghulta hai (100 g paani, 20 °C) | Cheeni lagbhag 204 g | Oxygen lagbhag 0.0009 g (bahut kam) |
| Ghol kaisa | Uniform (solution) | Uniform (solution) |
🚫 Misconceptions: Log aisa sochte hain… lekin
❌ Galat: “Saaf paani mein sirf H₂O hota hai, koi gas nahi.”
✅ Sach: nal, nadi, talaab ke paani mein hawa ki gases (oxygen, nitrogen, carbon dioxide) thodi matra mein ghuli hoti hain.
❌ Galat: “Machhli paani (H₂O) ke andar wali oxygen se saans leti hai.”
✅ Sach: machhli paani mein ghuli hui oxygen gas leti hai. Paani ke anu ki oxygen hydrogen se judi hai, machhli use alag nahi kar sakti.
❌ Galat: “Har cheez garam paani mein zyada ghulti hai.”
✅ Sach: gases ka ulta hai. Oxygen jaisi gases garam paani mein kam ghulti hain.
❌ Galat: “Paani garam karne par jo pehle chhote bulbule aate hain, woh bhaap hai.”
✅ Sach: ubaal se pehle ke chhote bulbule zyaadatar ghuli hawa ke hote hain. Bhaap ke bade bulbule ubaal ke paas bante hain.
❌ Galat: “Paani mein gas ka mel non-uniform hai, kyunki bulbule dikhte hain.”
✅ Sach: jab tak gas ghuli hai, woh dikhti nahi aur barabar faili hai, yaani uniform solution. Bulbule tab dikhte hain jab gas ghol se bahar nikal rahi hoti hai.
🔤 Key Terms (Exam mein English shabd hi likhna)
❓ FAQs
1. Kya oxygen paani mein ghulti hai?
Haan, lekin bahut thodi. 20 °C par 1 litre paani mein lagbhag 9 mg oxygen hi ghulti hai. Phir bhi yahi oxygen saare jaliya jeevan ko zinda rakhti hai.
2. Paani mein gas ka ghol uniform hai ya non-uniform?
Uniform. Ghuli gas paani mein barabar faili hoti hai aur alag se dikhti nahi. Isliye yeh ek solution hai.
3. Garmi mein machhliyaan satah par kyun aa jaati hain?
Garam paani mein oxygen kam ghulti hai, aur garmi mein machhliyon ko zyada oxygen chahiye. Satah ke paas paani mein hawa se taazi oxygen milti rehti hai, isliye woh upar aakar saans lene ki koshish karti hain.
4. Ubla hua paani thanda karke machhli ke bowl mein kyun nahi daalte?
Ubaalne par paani ki ghuli hawa (oxygen samet) lagbhag nikal jaati hai. Thanda hone par bhi turant wapas nahi ghulti. Aise paani mein machhli ko saans lene ke liye kaafi oxygen nahi milti.
5. Soda ki bottle kholne par bulbule kyun nikalte hain?
Bottle mein carbon dioxide zyada dabaav par ghuli hoti hai. Kholne par dabaav ghatta hai, gas ki solubility ghat jaati hai, aur extra gas bulbule banakar nikalti hai.
🧪 Activity: Paani mein chhupi hawa ko bahar nikaalo
Yeh demonstration activity hai: teacher ya kisi bade ki nigraani mein hi karein, kyunki isme garam karna padta hai.
Saamaan: saaf kaanch ka beaker (taaki andar dikhe), nal ka taaza paani, tripod stand, wire gauze, spirit lamp (ya gas), laboratory thermometer, ek aur beaker mein ubal kar thanda kiya hua paani (tulna ke liye).
Kya dikhega: taaze paani mein ubaal se pehle hi bahut saare chhote bulbule bante hain. Pehle se ubale paani mein yeh bulbule bahut kam bante hain.
Nishkarsh: taaze paani mein hawa ghuli thi. Garam karne par gases ki solubility ghati, toh ghuli hawa bulbule banakar bahar aayi. Ubale paani ki hawa pehle hi nikal chuki thi, isliye usme bulbule kam bane. Yani paani mein gases ghulti hain, aur garmi unhe bahar nikaal deti hai.
Yeh activity NCERT ki Class 8 Science book Curiosity (Chapter 9) ke “Solubility of Gases” wale hisse par aadharit hai, aur yahan apne shabdon mein samjhayi gayi hai. (NCERT ne is hisse mein alag se numbered activity nahi di hai, isliye yeh demonstration usi baat ko karke dikhata hai.)
🏠 Mini Experiments (Ghar pe)
Isse kya pata chala? Paani garam hua, ghuli hawa ki solubility ghati, aur hawa bulbule banakar bahar aa gayi.
Soda ki do chhoti bottlein lo: ek fridge mein thandi, ek kamre ke taapmaan par. Kisi bade ki madad se dono ko ek saath, do glass mein dheere se daalo. Kis glass mein zyada tez jhaag aur bulbule bane? Kaunsa pehle “flat” hua? Garam soda jaldi gas chhodti hai, kyunki garmi mein gas kam ghulti hai.
Soda ki band bottle ko halke se dabao: kadak lagti hai, kyunki andar dabaav hai. Kholo, “psssh!” suno. Ab dhakkan band karke 10 minute baad dabao: kam kadak. Dabaav nikla, gas bhi nikli.
🧠 Think Like a Scientist
Sawaal: Priya ke papa kehte hain ki ubla hua paani machhli ke liye theek nahi. Ek scientist ki tarah ise kaise jaanchoge, bina kisi machhli ko nuksaan pahunchaye?
Scientist ka tareeka dekho
1. Observe (dekho): taaza paani garam karne par ubaal se pehle chhote bulbule nikalte hain.
2. Guess (anumaan): yeh bulbule ghuli hawa hain. Agar ubaalne se hawa nikal jaati hai, toh ubala aur thanda kiya paani dobara garam karne par bahut kam chhote bulbule dega.
3. Test (jaanch): do beaker lo: A mein taaza nal ka paani, B mein ubal kar thanda kiya paani (dhak kar thanda kiya hua). Dono ko ek jaisi aanch par dheere garam karo aur 50 °C tak chhote bulbulon ko dhyaan se dekho.
4. Result: A mein bahut saare chhote bulbule, B mein bahut kam.
5. Conclusion: ubaalne se paani ki ghuli hawa (oxygen samet) nikal jaati hai. Isliye ubala paani machhli ke liye theek nahi. Papa sahi the, aur yeh hamne machhli ko chhue bina saabit kiya! 🔬
🌍 Real Life Mein Ghuli Gases
- 🐟 Talaab aur nadiyaan: garmiyon mein, khaaskar subah, talaab ki machhliyaan satah par aakar saans leti dikhti hain, kyunki garam paani mein oxygen kam hoti hai.
- 🏭 Garam paani ka pradushan: kuch factories aur bijli-ghar machine thandi karne wala garam paani nadi mein chhod dete hain. Isse nadi garam hoti hai, oxygen ghatti hai aur machhliyon ko nuksaan hota hai. Ise thermal pollution kehte hain.
- 🐠 Aquarium: pump (aerator) hawa ke bulbule daal kar paani mein oxygen badhata hai. Paani ke paudhe bhi din mein oxygen dete hain.
- 🥤 Soda aur cold drinks: carbon dioxide dabaav se gholi jaati hai. Bottle band aur thandi rakhne se gas der tak bachi rehti hai.
- 🌊 Thande samudra: dhruvon (poles) ke paas ka thanda samudri paani zyada oxygen sambhaal paata hai, isliye wahan jeevan bahut phalta-phoolta hai.
- 🌿 Paani ke paudhe: paani mein ghuli carbon dioxide se hi paani ke paudhe photosynthesis karke khaana banate hain.
🔁 Recap: Poora Post Ek Nazar Mein
- Oxygen, nitrogen, carbon dioxide jaisi gases paani mein ghulti hain. Paani solvent, gas solute.
- Oxygen bahut thodi ghulti hai (20 °C par 1 litre mein lagbhag 9 mg), phir bhi saara jaliya jeevan isi dissolved oxygen par tika hai.
- Machhli galphadon se ghuli oxygen gas leti hai, H₂O ke anu ki oxygen nahi.
- Gas ka paani mein ghol uniform mixture (solution) hai. Hawa bhi gases ka uniform mixture hai.
- Gases ke liye: taapmaan ⬆ → solubility ⬇. Thande paani mein zyada oxygen.
- Solids ke liye ulta: taapmaan ⬆ → solubility ⬆ (aam taur par).
- Dabaav ⬆ → gas ki solubility ⬆. Soda kholne par dabaav ghatta hai, gas bulbule banakar nikalti hai.
- Ubala paani, garam nadi aur garmi ka talaab: sab mein oxygen kam, machhliyon ko pareshani.
✍️ Fill in the Blanks
- Paani mein ghuli hui oxygen ko ______ oxygen kehte hain.
- Taapmaan badhne par gases ki solubility aam taur par ______ hai.
- Machhliyaan ______ (ang) ki madad se paani mein ghuli oxygen leti hain.
- Soda mein ______ gas dabaav daal kar gholi jaati hai.
- Paani mein gas ka ghol ek ______ mixture hai.
- Gas par dabaav badhaane se uski liquid mein solubility ______ hai.
Answers
1) dissolved (ghuli hui) · 2) ghatti · 3) galphade (gills) · 4) carbon dioxide · 5) uniform · 6) badhti
✅ True / False
- Oxygen garam paani mein thande paani se zyada ghulti hai.
- Hawa mein maujood alag-alag gases ka mel bhi ek uniform mixture hai.
- Oxygen paani mein bahut zyada matra mein ghulti hai.
- Ubaal aane se pehle bartan mein dikhne wale chhote bulbule zyaadatar ghuli hawa ke hote hain.
- Machhli paani ke anu (H₂O) ko tod kar oxygen leti hai.
- Thandi soda garam soda se zyada der tak fizzy rehti hai.
Answers (kyun ke saath)
1) False: ulta hai. Gases thande paani mein zyada ghulti hain. Sahi vaakya: oxygen thande paani mein garam paani se zyada ghulti hai.
2) True: hawa ki gases barabar mili hoti hain, alag-alag nahi dikhti.
3) False: oxygen bahut thodi ghulti hai, 20 °C par 1 litre mein lagbhag 9 mg.
4) True: garmi se ghuli hawa ki solubility ghatti hai aur woh bahar aati hai.
5) False: machhli paani mein ghuli oxygen gas leti hai.
6) True: thande paani mein carbon dioxide zyada ghuli reh sakti hai.
🔘 MCQs
Q1. Machhli saans lene ke liye kaunsi oxygen istemaal karti hai? (a) Paani ke anu (H₂O) ki oxygen (b) Paani mein ghuli oxygen gas (c) Sirf satah ki hawa, nathunon se (d) Paudhon ki jadon ki oxygen
✅ (b) Paani mein ghuli oxygen gas: galphade isi ko kheenchte hain.
(a) H₂O mein oxygen hydrogen se judi hai, machhli use alag nahi kar sakti.
(c) machhli hawa mein nahi, paani mein galphadon se saans leti hai.
(d) jadon se machhli ko oxygen nahi milti.
Q2. Taapmaan badhaane par paani mein gases ki solubility: (a) badhti hai (b) ghatti hai (c) barabar rehti hai (d) zero ho jaati hai
✅ (b) ghatti hai: garmi se gas ke kan urja paakar bahar nikal jaate hain.
(a) yeh zyaadatar solids ka niyam hai, gases ka nahi.
(c) taapmaan ka asar padta hai, barabar nahi rehti.
(d) ghatti hai, par garam paani mein bhi thodi gas ghuli rehti hai.
Q3. Kis paani mein sabse zyada oxygen ghuli ho sakti hai? (a) 40 °C (b) 30 °C (c) 20 °C (d) 5 °C
✅ (d) 5 °C: sabse thanda paani, sabse zyada ghuli gas.
(a) sabse garam, sabse kam oxygen.
(b) 40 °C se zyada, par 5 °C se kam.
(c) 30 °C se zyada, par 5 °C se kam.
Q4. Paani mein ghuli oxygen ka mel kis prakaar ka mixture hai? (a) Non-uniform mixture (b) Uniform mixture (solution) (c) Suspension (d) Pure substance
✅ (b) Uniform mixture (solution): gas barabar faili hai, alag nahi dikhti.
(a) non-uniform mein hisse alag dikhte hain, yahan nahi.
(c) suspension mein kan tairte ya neeche baith jaate hain, yahan aisa nahi.
(d) isme do cheezein (paani aur oxygen) hain, toh yeh pure substance nahi.
Q5. Soda ki bottle mein kaunsi gas ghuli hoti hai? (a) Oxygen (b) Nitrogen (c) Carbon dioxide (d) Hydrogen
✅ (c) Carbon dioxide: ise dabaav daal kar ghola jaata hai.
(a) oxygen soda ki fizz nahi banati.
(b) nitrogen soda mein nahi bhari jaati.
(d) soda ki fizz hydrogen se nahi, carbon dioxide se banti hai.
Q6. Aquarium mein air pump ka mukhya kaam kya hai? (a) Paani garam karna (b) Hawa ke bulbule se paani mein oxygen ka ghulna badhana (c) Paani mein namak milana (d) Machhli ko khaana dena
✅ (b): bulbule aur hilta paani hawa-paani ka sampark badhaate hain, zyada oxygen ghulti hai.
(a) pump garam nahi karta; garam paani mein toh oxygen aur ghategi.
(c) pump namak nahi milata.
(d) khaana alag se diya jaata hai.
Q7. Paani garam karte waqt ubaal se kaafi pehle dikhne wale chhote bulbule kya hain? (a) Paani ki bhaap (b) Ghuli hawa jo bahar nikal rahi hai (c) Bartan ke metal ke kan (d) Paani tootne se bani hydrogen
✅ (b) Ghuli hawa: garmi se uski solubility ghatti hai.
(a) bhaap ke bade bulbule ubaal ke paas bante hain.
(c) metal garam karne par bulbule nahi banata.
(d) saadhaaran garam karne se paani hydrogen aur oxygen mein nahi tootta.
Q8. 20 °C par 1 litre paani mein lagbhag kitni oxygen ghuli hoti hai? (a) 9 g (b) 9 mg (c) 204 g (d) 90 g
✅ (b) 9 mg: oxygen bahut thodi ghulti hai.
(a) 9 g sahi uttar se hazaar guna zyada hai.
(c) 204 g toh 100 g paani mein cheeni ki had hai, oxygen ki nahi.
(d) 90 g bahut zyada hai, oxygen itni nahi ghulti.
🔗 Assertion–Reason
Options: (a) A aur R dono sahi, aur R, A ko samjhata hai · (b) A aur R dono sahi, par R, A ko nahi samjhata · (c) A sahi, R galat · (d) A galat, R sahi
1. A: Garmiyon mein talaab ki machhliyaan aksar satah par aakar saans leti hain. R: Garam paani mein oxygen ki solubility kam hoti hai.
✅ (a): paani mein kam oxygen hone ki wajah se hi machhliyaan upar aati hain. R, A ka kaaran hai.
2. A: Soda ki bottle kholne par bulbule nikalte hain. R: Carbon dioxide paani mein bilkul nahi ghulti.
✅ (c): A sahi hai. R galat hai, carbon dioxide paani mein ghulti hai, khaaskar dabaav par. Dabaav ghatne par hi woh bahar aati hai.
3. A: Gases garam paani mein thande se zyada ghulti hain. R: Garam karne par paani ke kan zyada urja se hilte hain.
✅ (d): A galat hai, gases garam paani mein kam ghulti hain. R sahi hai, aur isi urja se gas ke kan bahar nikal jaate hain.
📝 Very Short Answer (1 mark)
1. Paani mein ghulne wali koi do gases ke naam likho.
Oxygen aur carbon dioxide (nitrogen bhi).
2. Dissolved oxygen kya hai?
Paani mein ghuli hui oxygen gas.
3. Thanda ya garam, kis paani mein zyada oxygen ghulti hai?
Thande paani mein.
4. Soda mein kaunsi gas hoti hai?
Carbon dioxide.
5. Kya paani mein oxygen ka ghol uniform hai?
Haan, yeh uniform mixture yaani solution hai.
📝 Short Answer (2–3 marks)
1. Oxygen paani mein bahut kam ghulti hai, phir bhi woh jaliya jeevan ke liye kyun zaroori hai?
Machhliyaan, jal-keede aur paani ke paudhe saans lene ke liye paani mein ghuli oxygen par hi nirbhar hain. Unke paas hawa se seedhe saans lene ka tareeka nahi hota. Isliye thodi si dissolved oxygen bhi unke liye jeevan hai.
2. Thande paani ka glass dhoop mein rakhne par uski deewar par bulbule kyun dikhte hain?
Dhoop se paani garam hota hai. Garmi badhne par ghuli hawa ki solubility ghatti hai, isliye extra hawa bulbule banakar bahar aati hai aur glass ki deewar par chipak jaati hai.
3. Solids aur gases ki solubility par taapmaan ka asar kaise alag hai?
Zyaadatar solids garam paani mein zyada ghulte hain (taapmaan ⬆, solubility ⬆). Gases garam paani mein kam ghulti hain (taapmaan ⬆, solubility ⬇). Jaise cheeni garam chai mein zyada ghulti hai, par oxygen garam paani se nikal jaati hai.
4. Ubala hua paani thanda karke machhli ke bowl mein daalna theek kyun nahi?
Ubaalne par paani ki ghuli hawa aur oxygen lagbhag nikal jaati hai aur jaldi wapas nahi ghulti. Aise paani mein machhli ko saans ke liye kaafi oxygen nahi milti.
📝 Long Answer (5 marks)
1. “Gases bhi paani mein ghulti hain” ise samjhao. Gas ki solubility par taapmaan ka asar, ek activity aur do real-life udaharan ke saath likho.
Ghulna: hawa ke sampark mein rehne wale paani mein oxygen, nitrogen aur carbon dioxide jaisi gases thodi matra mein ghul jaati hain. Paani solvent hai, gas solute, aur yeh ghol uniform (solution) hai. Oxygen bahut kam ghulti hai, 20 °C par 1 litre mein lagbhag 9 mg.
Taapmaan ka asar: gases ki solubility taapmaan badhne par ghatti hai. Garmi se gas ke kan urja paakar paani se bahar nikal jaate hain.
Activity: beaker mein taaza nal ka paani dheere garam karo. Ubaal se pehle hi tale aur deewaron par chhote bulbule bante hain. Yeh ghuli hawa hai jo garmi se nikal rahi hai. Pehle se ubala paani garam karne par aise bulbule bahut kam bante hain.
Udaharan: (i) garmiyon mein talaab ki machhliyaan satah par saans leti hain, kyunki garam paani mein oxygen kam hai. (ii) garam soda jaldi flat ho jaati hai, kyunki carbon dioxide garmi mein kam ghuli reh paati hai.
2. Paani mein oxygen kahan se aati hai, kahan jaati hai, aur kaun-kaun si cheezein ise kam kar deti hain? Machhliyon ko bachane ke do upaay bhi likho.
Kahan se aati hai: (i) hawa se, paani ki satah par ghul kar; lahrein, jharne aur behta paani isme madad karte hain. (ii) paani ke paudhe din mein photosynthesis karke oxygen chhodte hain.
Kahan jaati hai: machhliyaan, keede aur paudhe saans mein use karte hain; sadte kachre ko todne wale bacteria bhi oxygen khaate hain.
Kya kam karta hai: (i) garmi, kyunki garam paani mein gas kam ghulti hai; (ii) factories ka garam paani nadi mein chhodna (thermal pollution); (iii) gandagi aur sadta kachra; (iv) ruka hua, na hilne wala paani.
Upaay: (i) aquarium ya machhli palan ke talaab mein air pump/aerator lagana; (ii) nadiyon mein garam paani aur kachra na chhodna, aur talaab mein chhaaya ke liye kinare ped lagana.
📰 Case-Based Question
Bihar ke ek gaon mein Ramesh chacha machhli palan karte hain. Mai-June ki garmi mein ek din unhone dekha ki subah-subah talaab ki kai machhliyaan satah par aakar munh khol-band kar rahi thin. Machhli vibhaag ke adhikari ne salah di: “Talaab mein paddle wala aerator chalaiye, talaab mein naya thanda paani daaliye, aur subah ke samay machhliyon ko zyada khaana mat dijiye.” Do din mein machhliyaan theek ho gayin.
Q1. Machhliyaan satah par kyun aa rahi thin?
Garmi mein talaab ka paani garam ho gaya tha, isliye usme oxygen kam ghuli thi. Satah ke paas hawa se thodi taazi oxygen milti hai, isliye machhliyaan upar aakar saans le rahi thin.
Q2. Aerator chalaane se kya fayda hua?
Aerator paani ko hilaata hai aur hawa se sampark badhaata hai, jisse zyada oxygen paani mein ghulti hai.
Q3. Naya thanda paani daalne ki salah kyun di gayi?
Thande paani mein gases ki solubility zyada hoti hai, isliye thanda paani zyada oxygen sambhaal sakta hai aur talaab ka taapmaan bhi kam hota hai.
Q4. Subah ke samay oxygen sabse kam kyun hoti hai? (Hint: raat mein paudhe kya karte hain?)
Raat mein roshni nahi hoti, isliye paani ke paudhe photosynthesis karke oxygen nahi bana paate, lekin saans lete rehte hain. Machhliyaan aur bacteria bhi raat bhar oxygen use karte hain. Isliye subah tak oxygen sabse kam ho jaati hai.
🚀 HOTS
1. Ek factory nadi mein saaf, par garam paani chhodti hai. Paani mein koi zeher nahi hai, phir bhi neeche ki taraf machhliyaan kam ho gayin. Kyun?
Garam paani se nadi ka taapmaan badha aur oxygen ki solubility ghat gayi. Saath hi garmi mein machhliyon ko zyada oxygen chahiye. Zeher na hone par bhi oxygen ki kami se machhliyaan mar sakti hain ya door chali jaati hain. Ise thermal pollution kehte hain.
2. Pahaadi nadi ka paani maidaani talaab se zyada oxygen wala kyun hota hai?
Pahaadi nadi ka paani thanda hota hai aur tezi se behta, pattharon se takraata hai, jisse hawa paani mein khoob milti hai. Thanda paani aur zyada hawa ka sampark, dono oxygen badhaate hain. Ruka hua garam talaab ulta hota hai.
3. Rohan ne kaha, “Soda ki bottle ko fridge mein rakho, gas zyada der tak rahegi.” Kya woh sahi hai? Do kaaran do.
Haan. (i) Thande paani mein carbon dioxide ki solubility zyada hoti hai, isliye gas ghuli rehti hai. (ii) Band bottle mein dabaav bana rehta hai, jo gas ko ghula rakhta hai. Kholne ke baad bhi dhakkan jaldi band karke thanda rakhne se gas kam nikalti hai.
🏆 Olympiad Corner
1. In mein se kaunsi gas paani mein sabse zyada ghulti hai? (a) Oxygen (b) Nitrogen (c) Ammonia (d) Helium
✅ (c) Ammonia: ammonia paani mein bahut zyada ghulti hai. Oxygen, nitrogen aur helium bahut kam ghulti hain. Yaani “gases kam ghulti hain” har gas par barabar laagu nahi; har gas ki had alag hai.
2. 1 litre paani mein 0 °C par lagbhag 14.6 mg aur 40 °C par lagbhag 6.4 mg oxygen ghulti hai. 0 °C wala paani 40 °C wale se lagbhag kitne guna zyada oxygen rakhta hai?
14.6 ÷ 6.4 ≈ 2.3 guna. Yaani thanda paani do guna se bhi zyada oxygen sambhaal leta hai.
3. Oonche pahaad (jaise Ladakh) ki jheel mein, usi taapmaan par, samudra-tal ki jheel ke mukable ghuli oxygen kam kyun hoti hai?
Oonchaai par hawa ka dabaav kam hota hai. Gas ki solubility dabaav par nirbhar karti hai: kam dabaav, kam ghulna. Isliye usi taapmaan par bhi pahaadi jheel mein thodi kam oxygen ghulti hai.
Har option pe tap karo, turant pata chalega sahi ya galat.
Q1. 1 litre water mein ghuli oxygen: 10°C pe lagbhag 11.3 mg, 30°C pe lagbhag 7.6 mg. 10°C se 30°C hone pe kitni oxygen kam hui?
(a) 18.9 mg
❌ Galat: Dono values add kar di: 11.3 + 7.6 = 18.9. Kitni kam hui = 11.3 − 7.6 = 3.7.
(b) 7.6 mg
❌ Galat: 30°C wali value de di (7.6). Poocha kitni kam hui: 11.3 − 7.6 = 3.7.
(c) 3.7 mg
✅ Sahi! Kitni kam hui: 11.3 − 7.6 = 3.7 mg. Hot water kam oxygen pakadta hai.
(d) 11.3 mg
❌ Galat: 10°C wali value de di (11.3). Kitni kam hui: 11.3 − 7.6 = 3.7.
Q2. 20°C pe 1 litre water mein lagbhag 9 mg oxygen ghuli hoti hai. 5 litre water (20°C) mein lagbhag kitni?
(a) 9 mg
❌ Galat: 1 litre wali value hi de di (9). 5 litre: 9 × 5 = 45.
(b) 14 mg
❌ Galat: Multiply ki jagah add kiya: 9 + 5 = 14. Sahi: 9 × 5 = 45.
(c) 1.8 mg
❌ Galat: Divide kar diya: 9 ÷ 5 = 1.8. Zyada water, zyada oxygen: 9 × 5 = 45.
(d) 45 mg
✅ Sahi! 1 litre mein 9 mg, to 5 litre mein 9 × 5 = 45 mg.
Q3. Do fish tanks: ek 15°C ka, ek 35°C ka (baaki sab same). Kis tank mein fish ko kam oxygen milegi?
(a) 35°C wale mein: hot water mein kam oxygen ghulti hai
✅ Sahi! Gases ki solubility temperature badhne pe ghatti hai. 35°C ke water mein kam dissolved oxygen.
(b) 15°C wale mein: cold water mein kam oxygen ghulti hai
❌ Galat: Solids wala rule gas pe lagaya. Gas cold water mein zyada ghulti hai.
(c) Dono mein same: temperature se gas pe asar nahi
❌ Galat: Temperature ka asar ignore kiya. Hot water mein oxygen kam: 35°C wala.
(d) 15°C wale mein: fish H₂O tod ke oxygen leti hai
❌ Galat: Fish ko H₂O todne wala maana. Fish sirf ghuli oxygen gas leti hai; woh hot water mein kam.
Q4. Soda ki bottle kholte hi bubbles kyun nikalte hain?
(a) Temperature achanak badh gaya
❌ Galat: Pressure ki jagah temperature ko reason maana. Kholte hi temperature nahi badalta; pressure kam hota hai.
(b) Pressure kam hua, isliye CO₂ ki solubility kam hui
✅ Sahi! Band bottle mein CO₂ pressure se bhari hai. Kholte hi pressure kam: kam gas ghul paati hai, baaki bubbles ban ke nikalti hai.
(c) Water boil hone laga
❌ Galat: Bubbles ko boiling maana. Yeh ghuli CO₂ hai jo pressure kam hone pe nikalti hai.
(d) Bahar ki air andar ghus ke bubbles banati hai
❌ Galat: Air ko andar aata maana. Bubbles andar ghuli CO₂ ke hain jo bahar nikal rahi hai.
Q5. Water boil karke cool kiya aur fish ko usme rakha. Fish pareshaan kyun hoti hai?
(a) Boil karne se H₂O toot ke kam ho gaya
❌ Galat: Boiling ko H₂O todna maana. H₂O nahi toot-ta; ghuli oxygen gas nikal jaati hai.
(b) Boiled water mein oxygen zyada ho jaati hai
❌ Galat: Rule reverse lagaya. Heat karne pe gas kam ghulti hai, zyada nahi.
(c) Boil karne se ghuli oxygen bahar nikal gayi
✅ Sahi! Hot karne pe gas ki solubility ghatti hai: boiled water ki dissolved oxygen nikal jaati hai.
(d) Boil karne se water non-uniform ho gaya
❌ Galat: Boiling ko non-uniform banana maana. Water uniform hi hai; bas oxygen kam hai.
📚 Aur Padho (External Reference)
- NCERT Class 8 Science Curiosity, Chapter 9 (official PDF)
- DIKSHA: Sarkar ka free learning platform, NCERT ke videos ke liye
💖 CharuMam Motivation
Paani mein oxygen bas zara si hoti hai, ek litre mein kuch milligram. Dikhti bhi nahi. Phir bhi poori machhliyon ki duniya usi zara si cheez se saans leti hai.
Beta, aapki roz ki thodi si mehnat bhi aisi hi hai. Das minute revision, ek naya sawaal, ek doubt poochh lena: yeh sab chhota lagta hai, kisi ko dikhta bhi nahi. Lekin yahi chhupi hui “oxygen” aapke sapnon ko zinda rakhti hai. Aur yaad rakhna, gussa aur tension ki “garmi” mein dimaag ki oxygen bhi bhaag jaati hai. Thanda dimaag, zyada seekhna! 🌊
— CharuMam
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