Radiochemical Techniques Multiple Choice Questions and Answers

1. 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: Window width.

2. A quench curve can be constructed by plotting the counting efficiency versus ____________

a) Q-number

b) Quench factor

c) H-number

d) Disintegrations

Answer: H-number.

3. The reduction in counting efficiency of the scintillation detector is called as __________

a) Disintegration

b) Decay

c) Quenching

d) Reduction

Answer: Quenching.

4. In liquid scintillation counter, which of the following is a fluorescent substance?

a) Solvent

b) Solute

c) Crystal

d) Reagent

Answer: Solute.

5. 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: Colour quenching.

6. 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: Blue.

7. 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: Collision effect.

8. Which of these particles are highly penetrating?

a) Alpha particles

b) Beta particles

c) Gamma particles

d) X-ray particles

Answer: Gamma particles.

9. Which of the following is not a type of quenching?

a) Chemical quench

b) Interference quench

c) Colour quenching

d) Self-absorption

Answer: Interference quench.

10. 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: Photo multiplier tube.

11. 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: Self-absorption.

12. A discriminator circuit is which of the following circuits?

a) Wheatstone bridge

b) Instrumentation amplifier

c) Astable multivibrator

d) Schmitt trigger

Answer: Schmitt trigger.

13. 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: Counter.

14. 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: Rejects signals below a certain voltage.

15. 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: Anti-coincidence circuit

16. Schmitt triggers are followed by which of the following components?

a) Pre-amplifier

b) Linear amplifier

c) Anti-coincidence circuit

d) Discriminator

Answer: Anti-coincidence circuit.

17. 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: Parallel array of discriminators.

18. 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: Discriminators.

19. 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: Neutron to proton ratio.

20. 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: Alpha particles.

21. 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: Photoelectric effect.

22. 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: X-ray particles.

23. 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: Collision effect.

24. 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

d) 0.258/λ

Answer: 0.693/λ.

25. 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: Eliminate the need for chemical preparation.

26. Which of the following emissions have low ionizing power?

a) Alpha particles

b) Beta particles

c) Gamma particles

d) X-ray particles

Answer: Gamma particles.

27. Which of the following acts as ionising gas in Geiger Muller counter?

a) Alcohol

b) Argon gas

c) Krypton

d) Hydrogen

Answer: Argon gas.

28. 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: Polytetrafluoroethylene.

29. 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: Flame emission detector.

30. 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: Low energy beta materials

31. ‘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: Geiger Muller counter.

32. 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: It should be maintained at low temperature.

33. 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: Proportional counter.

34. Which of the following acts as quenching gas in Geiger Muller counter?

a) Alcohol

b) Argon gas

c) Krypton

d) Hydrogen

Answer: Alcohol.

35. 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: Krypton.

36. 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: Ampoules.

37. 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: Sodium chloride.

38. 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: Photoelectric effect.

39. 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: Anger camera.

40. 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: Position circuitry.

41. Which of the following is not a component of gamma camera?

a) Collimator

b) Detector crystal

c) Pre-amplifier

d) Position logic circuit

Answer: Pre-amplifier.

42. 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: Photo multiplier tubes.

43. 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: Scintillator along with a photo multiplier tube.

44. 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: Scintillation detector.

45. 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: Collimator.

46. Gamma camera uses one scintillation detector.

a) True

b) False

Answer: False.

47. Straight bore collimator is used for thyroid work in the medical field.

a) True

b) False

Answer: False.

48. Gaseous compounds containing radioactive sources can be directly introduced into the ionization chamber.

a) True

b) False

Answer: True.

49. When X-ray enters the solid state detector it produces ion pair rather than electron-hole pair.

a) True

b) False

Answer: False.

50. The basic unit used to describe the energy of a radiation particle is curie.

a) True

b) False

Answer: False.

51. Alpha emission is characteristic of heavier radioactive elements such as thorium, uranium, etc.

a) True

b) False

Answer: True.

52. Variation of gain with temperature does not cause instability.

a) True

b) False

Answer: False.

53. Photomultipliers used in Liquid scintillation detectors are a source of instability.

a) True

b) False

Answer: True.

54. If number of channels is more than ten, the problems of stability of discrimination voltages arise.

a) True

b) False

Answer: True.

55. The measurement of pulse height is useful for energy determination.

a) True

b) False

Answer: True