- i. The conversion of water into its vapour state.
- ii. The process of water changing from a liquid into gaseous state.
- iii. The formation of clouds from tiny water droplets.
- iv. The conversion of water vapour into its liquid state.
Condensation is the process in which water vapour changes into liquid water.
(iv) The conversion of water vapour into its liquid state.
Water colours, acrylic colours and ink dry because the liquid part evaporates. Crayons, pencil colours and ordinary pencil writing do not depend mainly on evaporation.
(i) Evaporation is very important while colouring with water colours and acrylic colours. (ii) Evaporation is very important while writing with an ink pen.
Evaporation causes cooling because heat is used when liquid water changes into vapour.
Natural grass contains water and loses water vapour through evaporation and transpiration. These processes absorb heat from the surroundings and make the area feel cooler. Plastic grass does not have water or transpiration, so it does not cool the surrounding air in the same way.
These liquids can change into vapour at ordinary temperatures, so they evaporate.
Examples include alcohol, perfume, petrol, nail-polish remover and hand sanitiser.
Evaporation depends on air movement. Faster air movement removes moist air and increases the rate of evaporation.
A fan helps wet clothes dry faster because moving air carries away water vapour from near the clothes. This allows more water to evaporate. Evaporation takes heat from the clothes and surroundings, so the clothes may feel cooler while drying even though the drying becomes faster.
Evaporation removes water from wet sludge. Less water means less mass and less mess, which reduces transport effort and handling risk.
When sludge is left in heaps, much of its water drains away or evaporates. The sludge becomes drier, lighter and less likely to spill. Therefore it is cheaper to transport and safer to handle. Drying also makes it easier to spread in a garden or field as manure.
Evaporation is faster with larger exposed area, higher temperature and greater air movement. These ideas are useful in daily drying and cooling activities.
Activities involving evaporation include drying clothes, drying a mopped floor, drying washed utensils, cooling sweat from our skin, drying wet hair, and drying grains or spices in sunlight. Understanding evaporation helps us dry things faster by spreading them out, keeping them in sunlight, or using moving air. It also helps us understand cooling by sweat and water.
The solid state of water is ice. Natural forms of ice include snow, hail and glaciers.
Water is present in the solid state in nature as ice, snow, hail, glaciers and frozen water on very cold surfaces or water bodies.
The chapter explains that only a small portion of water on Earth is fit for direct use and that increasing demand can cause water shortage.
Water is essential for life, so everyone has a right to use it. But this right comes with the responsibility to save water, avoid wasting it, keep water bodies clean and use water carefully so that plants, animals and other people also have enough clean water.
Evaporation causes cooling because liquid water uses heat from the surface while changing into vapour.
Sprinkle or wipe a little water on the seat and leave it for a short time, or wipe it with a wet cloth. As the water evaporates, it takes heat from the seat and cools it. Keeping the vehicle in shade will also help.