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Bhautik aur Rasaayanik Badlaav

Class 7 Science · Chapter 5: Hamare Aas-paas Badlaav: Bhautik aur Rasaayanik · NCERT Curiosity section 5.1–5.2

Seekho

Chhutti ki subah Meher kaagaz ki naav banaati hai, Ishaan gubbaara phulaata hai aur Neel rangoli ke liye chaak peeskar powder banaata hai. "Humne teen cheezein badli," Ishaan kehta hai. "Par kya kaagaz abhi bhi kaagaz aur chaak abhi bhi chaak hai?" Wo jaanchte hain: haan, sirf aakaar aur maap badla.

Jis badlaav mein padaarth ka aakaar, maap ya avastha badle par koi naya padaarth na bane, wo bhautik badlaav hai. Barf pighalna, paani ubaalna, kapde sookhna, sabzi kaatna aur cheeni ghulna sab bhautik badlaav. Barf, paani aur bhaap ek hi padaarth ki teen avasthaayein.

Ab Zoya straw se saaf choone ke paani mein dheere se phookti hai. Wo dheere-dheere doodhiya ho jaata hai! Saans mein carbon dioxide hai, jo calcium hydroxide (choone ka paani) se kriya karke calcium carbonate banaati hai, ek safed thos jo ghulta nahi. Naya padaarth bana: ye rasaayanik badlaav hai.

calcium hydroxide + carbon dioxide → calcium carbonate + water

Kabir thode sirke mein ek chammach baking soda daalta hai. Jhaag uthta hai! Gas ko choone ke paani mein guzaarne par wo doodhiya, to gas carbon dioxide hai. Rasaayanik badlaav ke sanket: gas ke bulbule, rang ya gandh badalna, garmi ya roshni nikalna, ya naya thos banna. Dahi jamaana, khaana pakaana, phal pakna aur jalna rasaayanik badlaav.

vinegar + baking soda → carbon dioxide + other substances

Explore: choone ke paani ki jaanch.

  1. Har gas jaanchkar sort karo.

Yaad rakho

  • Bhautik badlaav: sirf aakaar, maap ya avastha; naya padaarth nahi.
  • Rasaayanik badlaav: naye padaarth bante; carbon dioxide choone ka paani doodhiya karti.

Quick check

Inmein se kaunsa rasaayanik badlaav hai?

  1. doodh se dahi
  2. barf pighalna
  3. kaagaz modna
  4. cheeni ghulna
Answer

doodh se dahi. Dahi naya padaarth, naya swaad aur gandh.

Socho

Namak ka paani mein ghulna bhautik ya rasaayanik? Kaise jaanchoge?

Ek answer

Bhautik. Paani ko bhaap banaao to wahi namak bach jaata, to koi naya padaarth nahi bana.

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.