Answer the questions. 1. Who discovered phenomenon of radioactivity?

3. Translate the following words with the same root:

1)to consider, consideration, considerable, considerably; 2) to produce, production, productivity, product; 3) to depend, dependence, dependent, independent; 4) to use, use, useful, useless, usefulness; 5) to discover, discovery, discovered; 6) to add, addition, additional.

4.Open the brackets choosing the correct form of the Participles:

1. A positively (charging, charged) particle having the mass of the electron was discovered in 1932. 2. The scientist found that X-rays (produced, producing) were complex. 3. According to this theory (dealt with, dealing with) atomic structure the nucleus is a very small, compact, central part of an atom. 4. Oppositively (charged, charging) particles exert forces of attraction on one another. 5. Elements (composed, composing) of atoms containing only one or two valence electrons usually form positive ions. 6. (Investigated, investigating, having investigated) this phenomenon the scientists can make some important conclusions. 7. The work (doing, done) by these researchers resulted in many new discoveries. 8. The ions (involving, involved) can be used as a highly sensitive detector of radiation. 9. The investigation (followed, following) by many experiments was of great importance. 10. The nuclei (formed, forming) in this reaction are unstable.