Ex. 10. Translate the sentences into Russian paying attention to link-verbs.
1. Quartz is a hard, colourlcss substancc. 2. Silicic acid is a weak acid.
3. To break a crystal of quartz is to break some silicon-oxygcn bonds.
4. Silicon mostly occurs combined. 5. As chcmistry developed, some
hypotheses became laws. 6. An acid turns blue litmus red. 7. Watcr tums
into icc at 0°C. 8. Only a few of metals occur free in nature. 9. At boiling
point, water turns into vapour. 10. The students remained silent. 11. The
hypothesis holds true under different conditions. 12. The solution turns
yellow on standing. 13. He felt sorry for what he had done. 14. The
predictions proved right. IS. It was S p. m. and the classes were over.
16. Dalton’s atomic theory became one of the foundations of modem
chcmistry.
Ex. 11. Translate the sentences into English.
1. Кремний— однн из самых распространенных элементов на зем
ле. 2. Кремний встречается главным образом в виде диоксида крем
ния. 3. Кварц— это твердое бесцветное вещество. 4. Твердость квар
ца объясняется его структурой. 5. Структура кварца тесно связана со
структурой кремнекнслоты. 6. Кремнскислота — очень слабая кис
лота, она легко подвергается конденсации. 7. В кремнекнелоте крем
ний окружен четырьмя атомами кислорода и к каждому атому кисло
рода присоединен атом водорода.
Ex. 12. Make up two or three questions to the italicized parts of the
sentences.
1. Quartz
crystals arc identified as
right-handed or
left-handed (2).
2.
The structure of quartz and o f
other forms o f silica is described
as
consisting o fS i0 4 tetrahedra (3). 3.
In order to break a crystal o f quartz it
is necessary
to break some silicon-oxygen bonds (2).
Ex. 13. Answer the following questions:
1. In what state docs silicon occur? 2. What arc the physical properties
of quartz? 3. How is the hardness of quartz accounted for? 4. What do you
know about silicic acid? 5. Describe the molecular structure of SiOj.
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