Check yourself: atmosphere and hydrosphere
In this unit we studied substances (solid, liquid, gas), the composition and properties of air, the properties of water and water sources. Properties of air visible in ordinary conditions: gaseous, transparent, odourless, elastic, a poor conductor of heat, expands when heated. “Organic, liquid, smelly” are not properties of air. Gases may be lighter or heavier than air: helium, hydrogen and methane are lighter, carbon dioxide is heavier. Hydrogen and methane can explode, so they are dangerous; helium does not burn, which is why party balloons are filled with helium. A weather balloon studies the atmosphere, and a water treatment plant supplies clean water to homes. In water sugar dissolves, sand sinks and oil forms a layer on top.
“Quiz”: teams answer card questions on states of matter, air composition, water sources and water cleaning. One point for each correct answer.