Application of Radioactivity

Q.

The radioisotopes used for diagnosis in nuclear medicine

1. have short half-lives

2. travel rapidly through tissue

3. are usually gamma emitters

4. all of these

Q.

In a living organism, the C-14 concentration

1. remains approximately constant

2. continually increases

3. continually decreases

4. varies unpredictably during the lifetime of the organism

Q.

In a living organism, the C-14 concentration

1. remains approximately constant

2. continually increases

3. continually decreases

4. varies unpredictably during the lifetime of the organism

Q.

In a living organism, the C-14 concentration

1. remains approximately constant

2. continually increases

3. continually decreases

4. varies unpredictably during the lifetime of the organism

Q.

Food irradiation is used to

1. precook food

2. kill insects

3. increase nutrient value

4. kill micro-organisms

Q. Assume that the isotope $U^{238}$ and $U^{235}$ are found in the ratio 64 : 1 presently at a planet. At the time of the creation of the planet, they were present in an equal ratio.What is the age of the planet (in million years ${10}^6$ ). The half-life period of $U^{238}$ and $U^{235}$ are $4.45\times {10}^9$ and $7.0\times {10}^8$ year respectively.

Q. The basis of C-14 dating method is that the:

1. C-14 fraction is the same in all objects
2. C-14 is highly unstable and is readily lost from the objects
3. The ratio of C-14 and C-12 in our atmosphere has always been constant.
4. Living tissue will not absorb C-14 but will absorb C-12 from its source of carbon