**Physical and Chemical Properties of Water:** – Water is transparent, tasteless, odorless, and nearly colorless. – Chemical formula H2O indicates two hydrogen atoms connected to one oxygen atom. – Water covers about 71% of Earth’s surface. – Water exists in solid, liquid, and gaseous states on Earth. – Water plays a vital role in the global economy, agriculture, and food supply. – Water is used as a solvent in various industrial processes and cooking. – Water has specific thermal properties like boiling point, vapor pressure, thermal conductivity, refractive index, and viscosity. – Water has a hexagonal crystal structure and a bent molecular shape. – Water has a dipole moment and acidity/basicity properties. – Water is a polar inorganic compound and the universal solvent. **States and Properties of Water:** – Water molecule consists of two hydrogen atoms and one oxygen atom. – Water has three common states: solid (ice), liquid, and gas (water vapor). – Water becomes less dense as it freezes. – Ice has a density of 917kg/m³. – Water boils at 100°C and freezes at 0°C at 1 atm pressure. – Water can remain liquid at high temperatures in specific conditions. – Water is a diamagnetic material and exhibits phase transitions like melting and boiling. – Pressure affects the melting and boiling points of water. – Water has triple and critical points, including a supercritical fluid phase. **Chemical Properties and Solubility of Water:** – Water is poorly soluble in haloalkanes, aliphatic, and aromatic hydrocarbons. – Water has improved solubility in carboxylates, alcohols, ketones, and amines. – Water is miscible with substances like methanol, ethanol, and acetone. – Water is partially miscible with diethyl ether, methyl ethyl ketone, and ethyl acetate. – Water is a good polar solvent due to hydrogen bonding and molecular polarity. **Water Cycle and Resources:** – Water cycle involves processes like evaporation, transpiration, precipitation, and runoff. – Water resources include stocks like glaciers, groundwater, and flows like rivers and lakes. – Aquifers can store water for thousands of years, while lake volumes fluctuate seasonally. – Unsustainable groundwater withdrawals for irrigation lead to depletion. – Global freshwater distribution: glaciers (69%), groundwater (30%), other sources (1%). **Importance of Water in Life and Society:** – Water is essential for all known forms of life, metabolic processes, and replication. – Water is crucial for anabolism, catabolism, photosynthesis, respiration, and enzyme function. – Water supports diverse aquatic life forms and is central to ecosystems. – Access to safe drinking water is vital for human health and development. – Water scarcity, sanitation issues, and competition for water resources pose global challenges.https://en.wikipedia.org/wiki/Water