3.2. Match the notions and their definitions.

1. Isotope	a) property exhibited by certain types of matter of emitting energy and subatomic particles spontaneously. It is, in essence, an attribute of individual atomic nuclei
2. Radioactive isotope	b) radiochemical method of analysis for measuring the mass and quantity of an element in a substance. The procedure involves adding to a substance a known quantity of a radioisotope of the element to be measured and mixing it with the stable isotope of the element
3. Isotope dilution	c) in nuclear physics, any particle with one or more units of electric charge and a mass exceeding that of the helium-4 nucleus (alpha particle)
4. Protium	d) one of two or more species of atoms of a chemical element with the same atomic number and position in the periodic table and nearly identical chemical behaviour but with different atomic masses and physical properties
5. Deuterium	e) in physics and chemistry, a duplex of charged particles (ordinarily charged atoms or molecules), one positive, the other negative
6. Tritium	f) any of several species of the same chemical element with different masses whose nuclei are unstable and dissipate excess energy by spontaneously emitting radiation in the form of alpha, beta, and gamma rays
7. Radioactivity	g) isotope of hydrogen (q.v.) with atomic weight of approximately 1; its nucleus consists of only one proton
8. Ion	h) the isotope of hydrogen with atomic weight of approximately 3. Its nucleus, consisting of one proton and two neutrons, has triple the mass of the nucleus of ordinary hydrogen
9. Ion pair	i) any atom or group of atoms that bears one or more positive or negative electrical charges
10. Heavy ion	j) isotope of hydrogen with atomic weight of approximately 2. Its nucleus, consisting of one proton and one neutron, has double the mass of the nucleus of ordinary hydrogen

3.3. Match the verbs (1-10) with their synonyms (a-j).

1. differ a) vary

2. refer b) concern

3. use c) apply

4. exist d) subsist

5. research e) study

6. associate f) couple

7. contain g) comprise

8. complete h) conclude

9. retrieve i) recover

10. extend j) widen

11. verify k) examine

3.4. Translate the sentences below paying attention to the underlined patterns. Make up sentences of your own using these patterns.

1. In one way or another but you have to fulfill the experiment.

2. The Newton’s law of cooling isn’t shifted from year to year.

3. The professor doesn’t stir a finger to help students in integrating over the entire surface.

4. The professor set his hopes on these students.

5. The students gave all their attention to computerized method.