GENERAL REVISION

1. The amount of polonium to be obtained from a uranium mineral can be simply calculated.

2. We may suppose the alpha particles within the nucleus to be in motion.

3. This substance is reported to possess the property of radioactivity.

4. The speed of light being extremely great, we cannot measure it by ordinary means.

5. They will have to separate iron from sulphur with magnet.

6. The pipes to convey fluids are usually made of steel.

7. Galileo was the first to observe sun spots with his optic tube in 1609.

8. To translate ancient manuscripts was a very difficult task.

9. He was glad to have fulfilled his work ahead of time.

10. The isolation of radium followed by many important investigations made on other previously unknown elements proved to be of great importance.

11. Water being denser than air, rays is refracted towards the perpendicular.

12. Einstein computed the amount of scattering to be expected on the basis of the formula given above.

13. He was the first to determine the exact weight proportions of water components.

14. Other conditions being equal, the temperature remains the same.

15. The gas to be tested is enclosed in a long glass tube.

16. Once formed, bubbles rise because of the vapour being less dense than the liquid in which it is suspended.

17. Simple substances consist of atoms, each substance having its own special kind of atom.

18. More accurate experiments are likely to contribute significant information.

19. We have thought this law to hold only for gases that are under normal conditions.

20. They expected the acceleration to be different weights but this was not the case.

21. He seems to know this rule well.

22. The light from a star is known to have been coming to us for many years.

23. She might have tried to enter the University, but failed.

24. He must have obtained wrong results, because the professor was angry with him. He should have tested the device before the beginning of the experiment.

25. I can’t believe that he might have forgotten the order of instrument feeding.

28. The stuff of the laboratory is engaged in developing a new material now and thinks of improving properties of the obtained ones.

29. The professor approved student’s trying to solve the task in a different way.

30. The aim of the experiment consists in extracting some new substances from the given one.

31. He has done too much to give up experiments.

32. The painter is very proud of his work to stand any criticism.

33. This researcher was the first to discover the importance of quantitative analysis of chemical elements.

34. The engineer was proud to have found the best temperatures for the hot working of steel.

35. The term “pure metal” is used to describe a material from which all chemical elements but one has been eliminated.

36. The metals to be reduced resemble one another in their chemical properties.

37. Steel undergoes that treatment to improve its structure.

38. Only 30 grams of fuel are needed to keep the atomic station going for 24 hours.

39. A mean solar day is the mean time for the earth to make one rotation on its axis relative to the sun.

40. The purpose of a tension test is to determine the mechanical characteristics of any material.

41. The changes assumed to take place in making the experiment are illustrated in Fig. 1.

42. The apparatus is likely to give the results required.

43. The data thought to represent the results are sure to be obtained in practice.

44. Many substances are known to dissolve in hot water.

45. A substance, which is known to dissolve in acids, may not dissolve in water.

46. The substance reported to dissolve in hot water was thoroughly tested.

47. Substances thought to possess the property in question were thoroughly investigated.

48. Air pollution problem is one of the reasons why people are talking about eliminating the combustion engine altogether as soon as possible or at least reducing exhaust fumes.

49. There are designs that will help to overcome the problem of the time lost in recharging the accumulators, things like replacing the used-out battery in 10-15 minutes.

50. All these elements are radioactive, their atoms being unstable and undergoing spontaneous disintegration.

51. A new technique having been worked out, the income rose.