When an ionic compound such as sodium chloride (NaCl) is placed in water, the component atoms of the NaCl crystal dissociate into individual sodium ions (Na+) and chloride ions (Cl-). In contrast, the atoms of covalently bonded molecules (e.g., glucose, sucrose, glycerol) do not generally dissociate when placed in aqueous solution. Which of the following solutions would be expected to contain the greatest number of solute particles (molecules or ions)?

Water is essential for life. It makes up 60–75% of the human body, and a person can only survive 3 days without it.  Here are some properties of water that make it essential for life: Polarity: Water is polar, with slight positive and negative charges. This allows it to dissolve many polar and ionic substances. Heat capacity: Water absorbs and releases heat energy more slowly than many other substances. This helps moderate temperature changes within organisms and their environments. Universal solvent: Water's ability to dissolve many substances allows it to carry nutrients through the... Show more

Water is essential for life. It makes up 60–75% of the human body, and a person can only survive 3 days without it. 

Here are some properties of water that make it essential for life:
Polarity: Water is polar, with slight positive and negative charges. This allows it to dissolve many polar and ionic substances.
Heat capacity: Water absorbs and releases heat energy more slowly than many other substances. This helps moderate temperature changes within organisms and their environments.
Universal solvent: Water's ability to dissolve many substances allows it to carry nutrients through the water cycle.
Cohesion and adhesion: Water has high cohesion and adhesion.
Lower density when frozen: Water's density decreases when it freezes. 
Water also supports cell functions. All organisms are made of cells, and life's functions take place within cells. Chemical reactions are needed for life to gain energy, grow, and get rid of waste. Water is a liquid that allows these chemical reactions to take place. 

Water also plays many important roles in the body, including:
Flushing waste from the body
Regulating body temperature
Transporting nutrients
Digestion

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