Ex. 30. Answer the following questions.

1. When was D. I. Mendeleyev born? 2. Where was he born? 3. When did he go to gymnasium? 4. What subjects did he like? 5. What Institute did he enter? 6. Where did he work after the graduation from the Institute? 7. When was he granted the Doctor of Science degree? 8. What was he granted this degree for? 9. What was Mendeleyev’s greatest discovery? 10. What did he present to the Russian Chemical Society? 11. What other problems was Mendeleyev interested in? 12. What subjects did his numerous works deal with? 13. When did he die?

Ex. 31. Retell the text according to the following plan:

1. D. I. Mendeleyev's childhood.

2. The gymnasium and the Pedagogical Institute.

3. D. I. Mendeieyev's work at the Technological Insti­tute and at the University.,

4. His research work.

5. D. I. Mendeleyev's greatest discovery.

6. D. I. Mendeleyev's greatest contribution to science.

7. D. I. Mendeleyev is a great chemist and patriot.

Ex. 32. Insert this, that, these, those or it and translate the sentences:

1. ... terms are no longer associated with the origin of the substances. 2. ... phenomenon is not unknown in organic chemistry. 3. If ... two gases are mixed at high tem­peratures, a great amount of ... chemical substance is produced. 4. ... substance is far from ordinary and possesses a lot of highly interesting properties. 5. M. V. Lomonosov made brilliant discoveries at ... time. 6. Since ... time science and 'technology have made a great progress.

Ex. 33. Substitute that or these for the repeated noun:

1. Natural rubber is of higher quality than rubber produced artificially, 2. The chemists noticed the differences between substances derived from living matter and substances derived from materials. 3. Among the organic compounds the compounds containing only hydrogen and carbon, the so-called hydrocarbons, are the least reactive. 4. Physical changes are the changes which affect the state or condition of matter without changing its composition. 5. At temperatures higher than the temperatures mentioned before most substances melt or evaporate.

Study the following grammar rule.

Ex. 34. Translate the following instructions.

Laboratory Rules

1. Concentrate on your own experiment. Do not touch equipment which is not a part of your experiment. Do not move around more than necessary. Do not run.

2. Wear safety glasses. If your hair falls forward, tie it back.

3. Follow directions carefully. Make sure you are using the right amounts of the right chemicals. If you want to do an experiment of your own, check it out with your teacher.

4. Do not taste chemicals. Smell gases cautiously.

5. When heating a chemical in a test tube, be sure you are not pointing the test tube towards yourself or another pupil.

6. Write down your observations as soon as you have made them.

7. Use clean apparatus. Wash up and tidy up after a practical lesson. Put solid waste into the bins, not into the sinks. Let hot objects cool before putting them away.

8. If you have an accident, a burn, a cut or a splash of some chemical, wash with plenty of cold water. Tell your teacher immediately.

Date: 2016-01-03; view: 1197