Water and Atmosphere Quiz

Water and Atmosphere

• Water's chemical formula is H₂O
• Water is a transparent fluid
• Water is a major component of organisms' fluids
• A water molecule contains one oxygen and two hydrogen atoms
• Water exists in three physical states on Earth: liquid (lakes, oceans), solid (snow, ice), and gaseous (steam, water vapor)

Importance of Water for Living Things

• In some organisms, water accounts for up to 90% of their body weight
• Up to 60% of the human adult body and up to 50% of some plant tissues are water
• Water is found in many minerals
• 87% of milk is water

Properties of Water

• Pure water is transparent, colorless, tasteless, and odorless
• Pure water boils at 100°C and freezes at 0°C under standard atmospheric pressure
• Density of water is 1 cm³
• Water is a poor conductor of electricity
• Water is a universal solvent; it dissolves many substances (e.g., salt, sugar, oxygen, carbon dioxide, nitrogen)
• Most solids sink in liquid water
• Ice is less dense than liquid water—a characteristic that allows aquatic life to survive

Importance of Water for Human Bodies

• Water makes up over two-thirds of human body weight
• The human brain, blood, and lungs are largely composed of water (e.g., brain 95%, blood 82%, lungs 90%).
• Dehydration is a condition that results when the body loses more water than it takes in

Water Structure and Analysis

• Water can be separated using electricity and electrolysis
• Electrolysis involves filling an electrolysis cell with acidic water and passing an electric current through it
• This process electrically separates water into hydrogen and oxygen gases
• The volume of hydrogen gas produced is twice the volume of oxygen gas generated

Water Cycle

• Water evaporates from oceans, lakes, and rivers
• Evaporated water condenses into clouds
• Precipitation (rain, snow, hail, etc.) occurs
• Humidity is a measure of the amount of water vapor in the air, compared to the maximum amount possible. 100% humidity means the air is saturated, resulting in rain or fog.

How Wind Forms

• Weather is caused by the sun warming the Earth and atmosphere
• A sea breeze blows from the sea towards the land (during the day)
• Warm air rises over land, causing cooler, denser air to sink
• This creates a circular air current
• This cycle is reversed at night, with a land breeze blowing from land to sea

Clouds, Rain, and Storms

• Clouds form in three ways:
  • Warm air drifting over oceans towards mountains
  • One area of Earth heating up more than surrounding areas
  • A large mass of cold air moving under a warm, moist air mass, causing the warm air to rise.
• Hailstones are frozen raindrops formed in thunderstorms
• Tornadoes are funnel-shaped clouds that form during severe thunderstorms

Water Pollution

• Water pollution is the contamination of water bodies with harmful substances
• Point-source pollution comes from a single source.
• Nonpoint-source pollution comes from many sources
• Point source examples include trash dumping, slug dumping, oil spills.
• Nonpoint source pollution is difficult to control because it enters the water in many ways