LESSON TWO (OXYGEN)

Описание:

LESSON TWO
OXYGEN
This element is most widely distributed in nature; 49.85 per cent of the solid crust of the earth, 88.89 per cent of water and 20.8 per cent of air is oxygen. In nature it exists in limestone, sand, marble, clay, quartz, iron, and many other substances. It is prepared by heating certain of oxygen containing compounds, some of which are mercuric oxide, potassium chlorate and manganese dioxide; it may be obtained by the decomposition of water by electrolysis.
Oxygen is at ordinary temperature a colourless, odourless and tasteless gas, heavier than air and slightly soluble in water. 100 volumes of water, at 0º can dissolve 4 volumes of oxygen under the normal pressure of 760 mm. At a low temperature and a high pressure it is converted into a liquid which boils at -181ºC.

1. Ответьте на вопросы:
1. Is oxygen widely distributed in nature?
2. In what state does oxygen exist in air?
3. Where does oxygen exist in a combined state?
4. In what way is oxygen
prepared?
5. What are the substances oxygen may be prepared from?
6. What are the properties of oxygen?
7. Is oxygen lighter than air?
8. Is oxygen readily soluble in water?
9. How many volumes of water can dissolve 4 volumes of oxygen at 0º?
10. Under what conditions is oxygen converted into a liquid?
11. At what temperature does liquid oxygen boil?

2. Подберите антонимы:
1) to exist in a free state
2) high
3) soluble
4) to combine
5) low pressure
6) solid

3. Поставьте глаголы в скобках в нужную форму страдательного залога:
1) Oxygen ……. widely ……. ( distribute ) in nature.
2) In a combined state it ……. ( include ) in limestone, sand, marble, clay and
other substances.
3) Oxygen …….. ( prepare ) by heating certain of its compounds.
4) Decomposition of water by electrolysis …….. ( use ) for obtaining oxygen.
5) Oxygen … ( contain ) in air in a free state.
6) 4 volumes of oxygen can …… ( dissolve ) in water at 0 and the normal pressure.
7) Oxygen …… ( convert ) into a liquid at a low temperature and at a high
pressure.

4. Переставьте слоги в словах так, чтобы получились новые слова:
Tunare , soldi, denoxy , tonelimes, deoxi, rwate , lesscolour, vesoldis, liidqu,
repressu, slitlygh.

5. Поставьте вопросы к выделенным словам:
1) Oxygen is most widely distributed in nature.
2) It contains in limestone, sand, marble, clay, quartz and many other
substance.
3) Oxygen is at ordinary temperature a colourless, odourless and tasteless gas.
4) In air it exists in a free state.
5) It is prepared by heating certain of oxygen containing compounds.
6) Oxygen is slightly soluble in water

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