Water

Water (H₂O) is a universal solvent and one of the most essential compounds for life.
It covers about 71% of Earth's surface and is vital for drinking, agriculture, industry, and ecosystems.
In Bihar, water plays a central role in floods, irrigation, drinking supply, and flagship missions like Jal Jeevan Hariyali.

Basic Properties of Water

Chemical Formula: H₂O → 2 Hydrogen + 1 Oxygen atom
Colorless, odorless, and tasteless liquid at room temperature
Boiling point: 100°C, Freezing point: 0°C
Exhibits high surface tension, capillarity, and cohesive properties
Good conductor of electricity only when electrolytes are dissolved
Expands on freezing → Ice is less dense than water

📝 PYQ (BPSC): What is the formula of water? → H₂O
📝 Expected MCQ: Why does ice float on water? → Because it is less dense

Physical States of Water

Solid: Ice
Liquid: Water
Gas: Steam or water vapor
Water changes state via melting, evaporation, condensation, freezing

Roles of Water in Nature

🌿 Biological Functions

Medium for all life processes
Essential for photosynthesis, digestion, blood flow
Maintains body temperature and removes waste

🌧️ Environmental Cycles

Participates in Water Cycle → evaporation, condensation, precipitation
Supports climate regulation and weather patterns

Uses of Water

Drinking and sanitation
Agriculture → irrigation, crop growth
Industry → cooling, processing, chemical reactions
Energy → hydropower (e.g., Kosi Hydel Project)
Transport → rivers and canals used for inland navigation

📝 Expected MCQ: Water is a universal...? → Solvent
📝 Expected MCQ: Main component of blood plasma? → Water

Bihar-Specific Relevance

🚰 Water Supply & Sanitation

Government scheme: Jal Jeevan Hariyali Abhiyan
- Focus: groundwater recharge, pond rejuvenation, plantation
Nal Jal Yojana under Har Ghar Nal Ka Jal (7 Nishchay Yojana)

🌾 Agriculture

Water-intensive crops like paddy dominate Bihar's farm economy
Irrigation sources: canals, tubewells, rivers (Ganga, Kosi, Gandak)

🌊 Disasters

Bihar faces frequent floods in North Bihar due to Himalayan rivers
Waterlogged areas impact agriculture and public health

🧪 Education and Health

ORS (Oral Rehydration Solution) = Water + NaCl + Glucose → used to treat dehydration
Water purity and TDS (Total Dissolved Solids) monitoring in schools and hospitals

📝 Expected MCQ: Bihar’s mission to recharge water sources? → Jal Jeevan Hariyali
📝 Expected MCQ: Main crop requiring large water in Bihar? → Paddy

Water Purification Methods

Boiling: Kills pathogens
Chlorination: Disinfects water
Filtration & RO: Removes impurities
Distillation: Purest water, used in labs

📝 Expected MCQ: Which method gives the purest water? → Distillation

Important Water Bodies in Bihar

Rivers: Ganga, Gandak, Kosi, Sone, Punpun
Dams: Kosi Dam, Valmikinagar Dam
Lakes: Kanwar Lake (Asia’s largest oxbow lake)
Canals: Western Kosi Canal, Gandak Canal

📝 PYQ: Which is the largest lake in Bihar? → Kanwar Lake

PYQs + Expected MCQs

📝 PYQ (BPSC): What is the chemical formula of water? → H₂O
📝 PYQ (CDPO): What causes floods in North Bihar? → Himalayan Rivers
📝 Expected MCQ: Which scheme in Bihar focuses on water management? → Jal Jeevan Hariyali
📝 Expected MCQ: Which lake in Bihar is an oxbow lake? → Kanwar Lake
📝 Expected MCQ: What is ORS made of? → Water + Salt + Glucose
📝 Expected MCQ: What is the boiling point of water? → 100°C

Quick Revision Points

Water = H₂O → universal solvent
Exists in 3 states: solid, liquid, gas
Used in drinking, farming, industry, health
Bihar: floods, paddy farming, Jal Jeevan Hariyali
Purification: boiling, RO, chlorination, distillation
Kanwar Lake = largest in Bihar
ORS = Water + Salt + Glucose

Sources Used

NCERT Class 6–10 Science – Water & Its Importance
Lucent GK – Chemistry & Geography Sections
Drishti Science Quick Book
EduTeria + Ghatna Chakra BPSC PYQs
Jal Jeevan Hariyali – Govt of Bihar Official Site
Bihar State Disaster Management Authority
Bihar Economic Survey – Water Resources Section