A: The three states of water are solid (ice), liquid (water), and gas (water vapour). They differ in their shape, ability to flow, and ability to spread. Ice has a fixed shape, water takes the shape of its container but maintains volume, and water vapour spreads to fill available space.
Q: Explain the process of evaporation and its importance.
A: Evaporation is the process of water changing from liquid to gas at the surface. It’s important in the water cycle, cooling processes (like sweating), and many industrial applications. Evaporation occurs at all temperatures but happens faster at higher temperatures.
Q: What is condensation and how does it relate to cloud formation?
A: Condensation is the process of water vapour changing back to liquid water. In cloud formation, warm air rises and cools, causing water vapour to condense around dust particles in the air. As these droplets combine, they form visible clouds.
Q: How does the water cycle work?
A: The water cycle involves evaporation of water from surfaces like oceans and lakes, condensation of water vapour in the atmosphere to form clouds, precipitation as rain or snow, and the flow of water back to oceans through rivers or underground. This continuous cycle redistributes water around the Earth.
Q: What factors affect the rate of evaporation?
A: The rate of evaporation is affected by temperature, humidity, air movement (wind), and surface area exposed to air. Higher temperatures, lower humidity, stronger winds, and larger surface areas all increase the rate of evaporation.
Q: What is the difference between evaporation and boiling?
A: Evaporation occurs only at the surface of a liquid and can happen at any temperature. Boiling, on the other hand, occurs throughout the liquid when its vapor pressure equals the atmospheric pressure, typically at a specific temperature (100°C for water at sea level).
Q: Why is water conservation important?
A: Only a small portion of Earth’s water is freshwater suitable for human use. With increasing population and demand, many areas face water shortages. Conservation helps ensure sustainable water supply, protects ecosystems, and reduces the energy needed for water treatment and distribution.
Q: How does an earthen pot (matka) keep water cool?
A: An earthen pot keeps water cool through evaporative cooling. Water seeps through the porous clay and evaporates from the outer surface, taking heat from the water inside. This process continuously cools the water in the pot.
Q: What is humidity and how does it affect evaporation?
A: Humidity is the amount of water vapour present in the air. High humidity slows evaporation because the air is already saturated with water vapour. Low humidity increases evaporation as the air can accept more water vapour.
Q: How does freezing and melting relate to the states of water?
A: Freezing is the process of water changing from liquid to solid (ice) when cooled below 0°C. Melting is the reverse process, where ice changes back to liquid water when heated above 0°C. These processes involve the transition between two states of water.
Q: Why do clothes dry faster on a windy day?
A: Wind increases the rate of evaporation by continuously removing the layer of moist air near the wet clothes. This allows drier air to come in contact with the wet surface, speeding up the evaporation process and drying the clothes faster.
Q: How does understanding evaporation and condensation help in daily life?
A: Understanding these processes helps in many daily activities such as drying clothes, cooking (reducing sauces), using deodorants, and understanding weather patterns. It also aids in designing cooling systems, preventing moisture damage, and improving industrial processes.
Q: What role do dust particles play in cloud formation?
A: Dust particles serve as nuclei for water vapour condensation in the atmosphere. Water vapour condenses around these tiny particles, forming small water droplets. As more water vapour condenses on these droplets, they grow larger and eventually form visible clouds.
