Radiochemical Techniques

Question 1

1. Which of the following are highly effective in producing ion pairs when they pass through the matter?
   a) Alpha particles
   b) Beta particles
   c) Gamma particles
   d) X-ray particles

Answer 1

a) Alpha particles

Question 2

2. Which of the following can liberate photo electrons
   when they fall on certain metals?
   a) Alpha particles
   b) Beta particles
   c) Gamma particles
   d) X-ray particles

Answer 2

d) X-ray particles

Question 3

3. Which of these particles are highly penetrating?
   a) Alpha particles
   b) Beta particles
   c) Gamma particles
   d) X-ray particles

Answer 3

c) Gamma particles

Question 4

5. Which of the following is not a mode by which beta
   particles lose energy on interaction with matter?
   a) Photoelectric effect
   b) Compton effect
   c) Pair production
   d) Collision effect

Answer 4

d) Collision effect

Question 4

4. Alpha emission is characteristic of heavier radioactive elements such as thorium, uranium, etc.
   a) True
   b) False

Answer 4

a) True

Question 5

8. Which of the following formulae gives the expression for half-life of a radioactive isotope when ‘λ’ is the decay constant?
   a) 0.762/λ
   b) 0.693/λ
   c) 0.937/λ

Answer 5

b) 0.693/λ

Question 5

6. The stability of the nucleus can be predicted by which of the following?
   a) Electron to neutron ratio
   b) Neutron to proton ratio
   c) Proton to electron ratio
   d) Neutron to electron ratio

Answer 5

b) Neutron to proton ratio

Question 6

7. Which of the following is true about radiochemical
   methods?
   a) Eliminate the need for chemical preparation
   b) Not sensitive
   c) Not accurate
   d) Not specific

Answer 6

a) Eliminate the need for chemical preparation

Question 7

9. Which of the following emissions have low ionizing
   power?
   a) Alpha particles
   b) Beta particles
   c) Gamma particles
   d) X-ray particles

Answer 7

c) Gamma particles

Question 7

10. Which of the following effect occurs when a gamma ray and an electron make an elastic collision?
    a) Photoelectric effect
    b) Compton effect
    c) Pair production
    d) Collision effect

Answer 7

d) Collision effect

Question 8

1. Which of the following is not a type of radiation
   detectors?
   a) Geiger Muller counter
   b) Proportional counter
   c) Semiconductor detector
   d) Flame emission detector

Answer 8

d) Flame emission detector

Question 9

11. Which of the following effects transfers all the energy of the gamma ray to an electron in the inner orbit of the atom of the absorber?
    a) Photoelectric effect
    b) Compton effect
    c) Pair production
    d) Collision effect

Answer 9

a) Photoelectric effect

Question 10

12. The basic unit used to describe the energy of a
    radiation particle is curie.
    a) True
    b) False

Answer 10

b) False

Question 11

2. ‘When nuclear radiations pass through, gas ionization is produced.’ This is the principle of which of the following detectors?
   a) Proportional counter
   b) Flow counter
   c) Geiger Muller counter
   d) Scintillation counter

Answer 11

c) Geiger Muller counter

Question 12

3. Which of the following acts as quenching gas in Geiger Muller counter?
   a) Alcohol
   b) Argon gas
   c) Krypton
   d) Hydrogen

Answer 12

a) Alcohol

Question 13

4. Which of the following acts as ionising gas in Geiger
   Muller counter?
   a) Alcohol
   b) Argon gas
   c) Krypton
   d) Hydrogen

Answer 13

b) Argon gas

Question 14

5. Which of the detectors is similar to Geiger Muller
   counter in construction but is filled with heavier gas?
   a) Proportional counter
   b) Flow counter
   c) Semiconductor detector
   d) Scintillation counter

Answer 14

a) Proportional counter

Question 15

6. Which of the following gases are used in the
   proportional counter as the ionising gas?
   a) Alcohol
   b) Argon gas
   c) Krypton
   d) Hydrogen

Answer 15

c) Krypton

Question 16

7. Which of the following is the main disadvantage of solid
   state semiconductor detector?
   a) Low accuracy
   b) Low sensitivity
   c) It should be maintained at low temperature
   d) High pressure has to be produced

Answer 16

c) It should be maintained at low temperature

Question 16

8. Scintillation detector is a large flat crystal of which of
   the following materials?
   a) Sodium chloride
   b) Sodium iodide
   c) Sodium sulphate
   d) Sodium carbonate

Answer 16

a) Sodium chloride

Question 17

9. When X-ray enters the solid state detector it produces ion pair rather than electron-hole pair.
   a) True
   b) False

Answer 17

b) False

Question 18

11. Liquid samples must be counted using ionization
    chamber by placing them in which of the following?
    a) Test tube
    b) Curvette
    c) Ampoules
    d) Flask

Answer 18

c) Ampoules

Question 19

10. Which of the following materials are used as the
    insulation between the inner and outer electrodes of the ion chamber?
    a) Polythene
    b) Plastic
    c) Polytetrafluoroethylene
    d) Polyacrylamide

Answer 19

c) Polytetrafluoroethylene

Question 20

2. Which of the following is not a component of gamma camera?
   a) Collimator
   b) Detector crystal
   c) Pre-amplifier
   d) Position logic circuit

Answer 20

c) Pre-amplifier

Question 20

12. Gaseous compounds containing radioactive sources can be directly introduced into the ionization chamber. a) True b) False

Answer 20

a) True

Question 21

13. Liquid Scintillators are used for which of the following materials? a) Low energy beta materials b) High energy beta materials c) Low energy gamma materials d) High energy gamma materials

Answer 21

a) Low energy beta materials

Question 22

1. The first gamma camera is also known by which of the following names? a) Hal camera b) Anger camera c) Muller camera d) West camera

Answer 22

b) Anger camera

Question 23

3. Which of the following is the first object that an emitted gamma photon encounters after exciting the body? a) Collimator b) Detector crystal c) Photo multiplier tubes d) Position logic circuit

Answer 23

c) Photo multiplier tubes

Question 24

4. Which of the following is a pattern of holes through gamma ray absorbing material, usually lead or tungsten? a) Collimator b) Detector crystal c) Photo multiplier tubes d) Position circuitry

Answer 24

a) Collimator

Question 25

5. When the energy of an absorbed gamma photon is released, a flash of light is produced. This is similar to which of the following effects? a) Photoelectric effect b) Compton effect c) Pair production d) Collision effect

Answer 25

a) Photoelectric effect

Question 26

6. Which of the following components adds all the signals and determines where each scintillation event occurred in the detector? a) Collimator b) Detector crystal c) Photo multiplier tubes d) Position circuitry

Answer 26

d) Position circuitry

Question 27

7. Gamma camera uses one scintillation detector. a) True b) False

Answer 27

b) False

Question 28

8. Gamma camera uses which of these components to produce a position intensity picture of a radioactive area? a) Collimator b) Scintillation detector c) Photo multiplier tubes d) Position circuitry

Answer 28

b) Scintillation detector

Question 29

10. Straight bore collimator is used for thyroid work in the medical field. a) True b) False

Answer 29

b) False

Question 29

1. In liquid scintillation counter, which of the following is a fluorescent substance? a) Solvent b) Solute c) Crystal d) Reagent

Answer 29

b) Solute

Question 30

9. Which of the following is known as a scintillation counter? a) Scintillator b) Scintillator along with a photo multiplier tube c) Scintillator along with the crystal d) Scintillator along with position circuitry

Answer 30

b) Scintillator along with a photo multiplier tube

Question 31

4. The reduction in counting efficiency of the scintillation detector is called as __________ a) Disintegration b) Decay c) Quenching d) Reduction

Answer 31

c) Quenching

Question 31

2. When UV light is absorbed by the fluor molecules the light emitted is in which of the following colours? a) Pink b) Red c) Green d) Blue

Answer 31

d) Blue

Question 32

3. In liquid scintillation counter, which of the following is used to convert light into electrical signals? a) Photo multiplier tube b) Photo emissive tube c) Photo voltaic cell d) Photo reflector

Answer 32

a) Photo multiplier tube

Question 33

5. Which of the following is not a type of quenching? a) Chemical quench b) Interference quench c) Colour quenching d) Self-absorption

Answer 33

b) Interference quench

Question 34

6. In which type of quenching, the radiation emitted by the isotope is not detected due to absorption of the radiation by the sample itself? a) Chemical quench b) Interference quench c) Colour quenching d) Self-absorption

Answer 34

d) Self-absorption

Question 35

7. Variation of gain with temperature does not cause instability. a) True b) False

Answer 35

b) False

Question 36

8. Due to the presence of red, green and yellow colour in the vial, which of the following occurs? a) Chemical quench b) Interference quench c) Colour quenching d) Self-absorption

Answer 36

c) Colour quenching

Question 37

1. A discriminator circuit is which of the following circuits? a) Wheatstone bridge b) Instrumentation amplifier c) Astable multivibrator d) Schmitt trigger

Answer 37

d) Schmitt trigger

Question 38

9. A quench curve can be constructed by plotting the counting efficiency versus ____________ a) Q-number b) Quench factor c) H-number d) Disintegrations

Answer 38

c) H-number

Question 39

10. Photomultipliers used in Liquid scintillation detectors are a source of instability. a) True b) False

Answer 39

a) True

Question 40

2. Which of the following is the function of the discriminator? a) Rejects signals below a certain voltage b) Rejects signals above a certain voltage c) Rejects signal in a range alone d) Filters noise alone

Answer 40

a) Rejects signals below a certain voltage

Question 41

3. The difference between the pulses having amplitudes between the two triggering levels is called __________ a) Pulse width b) Energy gap c) Window width d) Amplitude variation

Answer 41

c) Window width

Question 42

4. The pulses having amplitudes between the two triggering levels are given by which of the following components? a) Pre-amplifiers b) Linear amplifiers c) Anti-coincidence circuits d) Discriminators

Answer 42

d) Discriminators

Question 43

5. Schmitt triggers are followed by which of the following components? a) Pre-amplifier b) Linear amplifier c) Anti-coincidence circuit d) Discriminator

Answer 43

c) Anti-coincidence circuit

Question 44

6. Which of the following components cancels all the pulses which trigger both the discriminators? a) Pre-amplifier b) Linear amplifier c) Anti-coincidence circuit d) Discriminator

Answer 44

c) Anti-coincidence circuit

Question 45

8. If number of channels is more than ten, the problems of stability of discrimination voltages arise. a) True b) False

Answer 45

a) True

Question 45

7. Which of the following is used when the number of channels is ten or less? a) Two discriminators in series b) Two discriminators in parallel c) Series array of discriminators d) Parallel array of discriminators

Answer 45

d) Parallel array of discriminators

Question 46

9. The signal reaching which of the following components is the one lying in the window of pulse height analyser? a) Pre-amplifier b) Linear amplifier c) Counter d) Discriminator

Answer 46

c) Counter

Question 47

10. The measurement of pulse height is useful for energy determination. a) True b) False

Answer 47

a) True