Paani

**Paani** ek inorganic compound hae, jiske chemical formula H2O hae. Paani jhillarr (transparent), besawaad, bina gandh ke, aur berang chemical substance hae. Ii dunia ke  hydrosphere ke main constituent hae aur ii sab jinda chij me rahe hae. Kaaheki paani ek polar molecule hae, ii tagrraa intermolecular  hydrogen bond banae hae, jon iske   physical aur chemical properties ke khaas kaaran hae.  Ii sab rakam ke jiu khaatir jaruri hae, lekin ii khaana waala taagat nai de hae. Kaaheki ii sab jiu me hae, chemically stable hae, ii dunia bhar me paawa jaawe hae, iske tagrraa polarity hae, paani ke "universal solvent" bola jaawe hae. 

Kaaheki dunia ke waatawaran, paani ke triple point ke nagiich hae, dunia me paani tiino  solid, a liquid, aur gas ke ruup me rahe hae. Paani se barsaat aur fog hoe hae. Baadal me paani aur ice ke chhota-chhota droplet rahe hae. Jab ice ke aur chhota karaa jaawe hae tab ii snow ban jaawe hae. Paani ke gas ke state bharf hae.  

Paani, dunia ke 71.0% surface ke cover kare hae, aur  samundar aur mahaasaagar me iske lagbhag 96.5%nvolume hae. Thhorraa paani jamiin ke niche rahe hae (1.7%), glaciers aur  Antarctica aur Greenland ke icecap (1.7%), hawaa me bharf ke ruup me , baadal , aur barsaat (0.001%). Paani sab samay water cycle, jisme evaporation, transpiration (evapotranspiration), condensation, precipitation, aur runoff hae, me rahe hae.

Paani, dunia ke economy me ek khaas role play kare hae. Insaan ke kaam me laae waala paani ke  70% ke khet ke siche ke khaatir kaam me laawa jaawe hae.  Khaara paani aur mitthaa paani me machhri maarna dunia ke dher hissa me khaana ke ek important source hae, jisse dunia ke 6.5% of protein mile hae. Jaada, tradeboat se, jon samundar, naddi, talaab aur khaarri me se jaawe hae, se karaa jaawe hae.  Industry aur ghar ke garmaae aur thandaa kare ke khaatir dher paani ke kaam me laawa jaawe hae.  Paani, dher chij ke khaatir solvent ke ruup me kaam me laawa jaawe hae, aur ii kaaran se iske dher  industrial processes jaise khaana pakaana aur dhoe ke khaatir kaam me laawa jaawe hae.  Paani, ice, aur snow ke dher khel-kuud, jaise  pahurrnaa, nao chalaana, boat racing, surfing, sport fishing, diving, ice skating, snowboarding, aur skiing ke khaatir kaam me laawa jaawe hae.

## Itihaas
### Dunia pe
Ek chij jon jon ii anumaan lagae me ki dunia me kab pahile paani aais, ke hard kare hae ki paani ke sab time space se khiy dewa jaawe hae. Atmosphere me H2O molecule photosynthesis se tuute hae aur jon hydrogen atom bane hae kabhi-kabhi dunia ke gravitational pull se baaha rchal de hae. Jab dunia chhotaa rahaa aur kamtii garrhu rahaa tab paani ke space me aur sahaj se khoe dewa jaawat rahaa.  Halluk element jaise hydrogen aur helium ke expect karaa jaawe hae ki ii atmosphere se sab time leak karii, lekin aur garrhu   noble gases jon atmosphere me hae ii  suggest kare hae ki aur garrhu pahile ke  elements in atmosphere me se space me herae jaaweat rahaa. Xenon khaas kar ke paani ke space me khoe ke calculation me important hae. Ii khaali ek nai hae noble gas (aur atmosphere se chemical reactions se nai nikaala jaawe hae ), lekin iske nau stable isotope ketna maatra me hae  ke compare kar ke ii paawa jaawe hae ki dunia kamti-sekamti ek ocean bhar ke paani ke aapan puraana itihaas me khois hae. Ii jaada likely hae ki  Hadean aur Archean eons ke biich me, koi cataclysmic events jaise chandarma ke bane ke impact, ketime bhais rahaa.

Dunia me koi bhi paani accretion ke duusra bhaag me Moon-forming impact (~4.5 billion years ago), jon likely Earth ke  crust aur upper mantle ke vaporise  kar dewa gaus rahaa hoi. Ii patthar ke   vapor dui hazaar saal me paani ban gae rahaa hoi, aapan pichhe  garam volatileschhorr ke jiske kaaran jaada carbon dioxide waala atmosphere jisme hydrogen aur bhaap rahaa, banaa rahaa.. Baad me , liquid paani waala sagar rahaa hoi  surface temperature of   rahe par bhi jaada atmospheric pressure  CO2 atmosphere ke kaaran. Jaise jaise dunia thandaa bhais jaada CO2  atmosphere se subduction ke kaaran hatae dewa gais rahaa aur ocean ke paani me dissolve hoe e kaaran, lekin ii level uppar niche jaate rahaajaise nawaa new surface aur mantle suruu bhais.

## References