Properties of Oxygen
This element is the most widely distributed in nature. 47.3 per cent of the solid crust of the earth, 88.81 per cent of water and 23.15 per cent of air are composed of oxygen. In air it exists in a free state. In a combined state it presents in limestone, sand, marble, clay, quartz, iron, and many other substances. We can obtain it when heating certain of its compounds, some of which are mercuric oxide, potassium chlorate and mangenese dioxide. It may be prepared by the decomposition of water by electrolysis. At an ordinary temperature oxygen is colourless, odourless and tasteless gas, heavier than air and slightly soluble in water. It is interesting to note that at a low temperature and a high pressure it is converted into a liquid boiling at - 181° C.
Oxygen is an element following nitrogen. To call more important element in our life than oxygen is difficult. The physical properties of oxygen were studied long before its chemical properties. By its chemical behaviour oxygen is very reactive. Combining with an element oxygen forms an oxide. The process is called oxidation. There are only few elements not attacked by oxygen. Oxygen combines with almost all other substances liberating heat and light. This process is known as combustion. Oxygen was used as the basis of the atomic weights of other elements.
Задание 2: Перепишите предложения, подчеркните в каждом инфинитив и укажите его функцию, т.е. определите, будет ли инфинитив подлежащим, обстоятельством, определением или частью составного именного сказуемого. Предложения переведите.
Penicillin was the first antibiotic to give good results in the treatment of pneumonia.
To become a good specialist we study different subjects.
The aim of our experiment was to compound medicines.
The ampoule of glucose to be used in treatment was placed in a refrigerator.
To test the substance was not an easy task.
Задание 3: Перепишите предложения, подчеркните Participle I, укажите его функцию, т. е. определите, будет ли оно определением, обстоятельством или составной частью сказуемого.
We were measuring that distance with great accuracy.
Medicines having an organic structure are taken before meal-time.
Being of good quality the ointment is recommended in many cases.
Задание 4: Перепишите предложения; подчеркните глагол-сказуемое и определите его видовременную форму и залог; напишите форму инфинитива. Предложения переведите.
Side effects are becoming more and more intensive in some cases.
Doctor entered the ward when the temperature of the patient was being taken.
What were you solving yesterday morning from 11 to 12 o’clock?
This time tomorrow the assistant will be finishing the test for purity.
The distillation of sea water is being used more and more widely.
Задание 5: Перепишите предложения, подчеркните глагол to do и определите, является ли он смысловым, вспомогательным или словом заместителем. Предложения переведите.
Не always does the injection of insulin in time.
This experiment gave more accurate data than the previous one did.
Do you know the properties of this lotion?
Задание 6: Выпишите предложения, где конструкции с глаголами to have, to be выражают долженствование, предложения переведите.
Не was told to be in time.
This analgesic has wide application.
Fresh air and sport are good for health.
The treatment is not to be interrupted without doctor's advice.
A first year student has to carry out a number of experiments in the laboratory of general chemistry.
Задание 7: Перепишите предложения, подчеркните в каждом придаточное предложение; подчинительный союз или союзное слово обведите кружком; при бессоюзном подчинении укажите на место, где мог бы находиться опущенный союз. Предложения переведите.
The elements carbon dioxide is composed of are carbon and oxygen.
We know that heat is the form of motion.
The process oxygen takes part in is known as oxidation.
Sodium nitrate is very sensitive to moisture which at once turns it while with liberation of ammonia.