Across
- 6. the chemical element of atomic number 15, a poisonous, combustible non-metal which exists in two common allotropic forms, white phosphorus, a yellowish waxy solid which ignites spontaneously in air and glows in the dark, and red phosphorus, a less reactive form used in making matches.
- 9. the upper layer of earth in which plants grow, a black or dark brown material typically consisting of a mixture of organic remains, clay, and rock particles.
- 14. a process in living organisms involving the production of energy, typically with the intake of oxygen and the release of carbon dioxide from the oxidation of complex organic substances.
- 16. the invisible gaseous substance surrounding the earth, a mixture mainly of oxygen and nitrogen.
- 17. organisms whose cells have a nucleus enclosed within a nuclear envelope.
- 18. of or containing nitrogen with a lower valency, often three
- 19. a stock or supply of money, materials, staff, and other assets that can be drawn on by a person or organization in order to function effectively.
- 20. that has formed from sediment deposited by water or air.
- 22. colourless unstable toxic gas with a pungent odour and powerful oxidizing properties, formed from oxygen by electrical discharges or ultraviolet light. It differs from normal oxygen (O2) in having three atoms in its molecule (O3).
- 24. fully or partly halogenated paraffin hydrocarbons that contain only carbon, hydrogen, chlorine, and fluorine, produced as volatile derivatives of methane, ethane, and propane.
- 25. a binary compound of oxygen with another element or group.
Down
- 1. the process where organic forms of nitrogen are converted to NH4+
- 2. a series of events that are regularly repeated in the same order.
- 3. Acid rain is rain or any other form of precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions.
- 4. the degree or intensity of heat present in a substance or object, especially as expressed according to a comparative scale and shown by a thermometer or perceived by touch.
- 5. water which collects as droplets on a cold surface when humid air is in contact with it.
- 7. the presence in or introduction into the environment of a substance which has harmful or poisonous effects.
- 8. the organic component of soil, formed by the decomposition of leaves and other plant material by soil microorganisms
- 10. a person or thing that eats or uses something.
- 11. the layer of the earth's atmosphere above the troposphere, extending to about 50 km above the earth's surface (the lower boundary of the mesosphere).
- 12. a gentle wind.
- 13. the process of turning from liquid into vapour.
- 15. colourless, odourless reactive gas, the chemical element of atomic number 8 and the life-supporting component of the air.
- 21. the draining away of water (or substances carried in it) from the surface of an area of land, a building or structure, etc.
- 23. the process by which green plants and some other organisms use sunlight to synthesize nutrients from carbon dioxide and water.