Answer the questions. 1. Has powder a definite shape?

1. Has powder a definite shape?

2. What do we see if we examine common salt under a microscope?

3. What do we call crystals?

4. Is solid a crystalline substance?

5. What can you say about chalk?

6. What is a crystal of common salt composed of?

7. How are sodium and chlorine ions arranged in a crystal?

2. Give synonyms:

quantity, to call, several, to approach, some, to reach, various, to show, to name, different, to indicate, shape, form, characteristic, number, property, to use, value, generally, ordinarily, to apply, amount.

3. Translate the following sentences:

1. Since a little piece of salt has been examined under a microscope, it was established that it consisted of tiny cubes. 2. Many experiments with different solids were carried out in Middle Ages, since then a great many experimental methods have been developed. 3. Radioactivity is a natural process that has been investigated since the end of the last century. 4. The sum of the charges of proton and electron is equal to that of neutron. 5. The free energy of the reactants is equal to that of the products obtained. 6. Common salt consists of tiny cubes, some of them being perfect ones. 7. A mechanical method was followed by an electrical one. 8. The behaviour of aluminium is similar to that of zinc. 9. The values of the boiling-points are those carefully determined by us, and those of the molecular volumes have been taken from Lassen's data.