Ulte Hone Wale, Sthaayi aur Vaanchhit Badlaav
Class 7 Science · Chapter 5: Hamare Aas-paas Badlaav: Bhautik aur Rasaayanik · NCERT Curiosity section 5.4–5.6
Seekho
Ishaan gubbaare ki hawa nikaalta hai: wo waapas chhota. Meher naav kholti hai: phir chapta kaagaz. Kuch badlaav ulte ho sakte: wahi cheez ya padaarth waapas milta. Pighli barf phir jamaai ja sakti; bhaap phir paani ban sakti.
Par kati sabzi phir nahi judti, idli phir ghol nahi banti, aur raakh phir kaagaz nahi banti. Ye ulte na hone wale badlaav. Zyaadatar rasaayanik badlaav, jaise pakaana aur jalaana, ulte nahi hote, par kuch bhautik bhi, jaise kaatna, gehoon peeskar aata, ya gubbaara phodna.
Kuch badlaav madad karte, kuch nuksaan. Dahi jamaana, phal pakna, khaana pakaana aur rasoi ke kachre se compost vaanchhit. Auzaaron par jung, khaana sadna, aur gaadiyon-kaarkhaanon mein eendhan jalne se zyaada carbon dioxide aur dhuaan avaanchhit. Hum jung rokne ko loha paint karte aur sadna dheema karne ko khaana thanda rakhte.
Explore: kya ulta ho sakta?
- Har badlaav sort karo.
Yaad rakho
- Ulte hone wale badlaav waapas ho sakte; ulte na hone wale nahi, bhautik ho ya rasaayanik.
- Vaanchhit badlaav kaam ke (dahi, compost); avaanchhit nuksaan karte (jung, sadna, pradooshan).
Quick check
Gehoon peeskar aata banaana …
- bhautik badlaav jo ulta nahi ho sakta
- rasaayanik badlaav
- ulta hone wala badlaav
- badlaav nahi
Answer
bhautik badlaav jo ulta nahi ho sakta. Naya padaarth nahi, par daane waapas nahi milte.
Socho
Phal pakna vaanchhit, par zyaada pakna nahi. Isse kya pata chalta?
Ek answer
Badlaav vaanchhit hai ya nahi, ye is par nirbhar ki wo kitna aage jaata aur hamari zaroorat kya; ek hi badlaav ek had tak kaam ka aur uske baad nuksaandeh ho sakta.
Practice
Teen levels (easy, medium, hard) ke naye sawaalon se practice karo, kuch hands-on, hints aur hal ke saath. Topic poora karne ke liye pichhle 5 mein se 4 sahi karo.