Sampling principles for solids, liquids and gases and hazards of sampling - Question Bank

1. When sampling solids from a conveyor belt, what is the best practice for obtaining a representative sample?
A) Scoop a small amount from the middle
B) Take a full cross-section of the material at regular intervals
C) Collect material that falls off the edge
D) Sample only at the beginning of the belt
2. What is a common hazard associated with sampling fine powders that are electrostatically charged?
A) Explosion due to static discharge igniting dust
B) High viscosity
C) Corrosion of equipment
D) Low vapor pressure
3. Which sampling method is often used for large, static bodies of liquid like lakes or large tanks?
A) Single point grab sampling
B) Systematic sampling
C) Stratified sampling
D) Composite sampling
4. What is the primary goal of a 'representative sample'?
A) To be easy to analyze
B) To be collected quickly
C) To accurately represent the composition of the entire lot
D) To be visually appealing
5. When collecting a gas sample in a cylinder, what is important to prevent?
A) Leakage from the cylinder
B) Condensation of sample components
C) Evaporation of the gas
D) Overfilling the cylinder
6. What is a key safety precaution when sampling materials that are radioactive?
A) Wearing standard gloves
B) Minimizing exposure time and maximizing distance
C) Sampling in a high-temperature environment
D) Using a large volume sampling container
7. Which type of sampling is suitable for a large pile of granular material where composition is expected to be uniform throughout?
A) Stratified sampling
B) Systematic sampling
C) Random sampling
D) Composite sampling
8. What does 'sampling bias' imply?
A) The sample is too small
B) The sampling method systematically favors certain parts of the material
C) The analytical instrument is faulty
D) The data is incorrectly recorded
9. When sampling gases, what is the primary concern with using a flexible plastic bag?
A) Permeation of gases through the bag material
B) High cost
C) Difficulty in handling
D) Low capacity
10. What is a major hazard when sampling hot liquids?
A) Freezing of the sample
B) Burns from hot liquid or steam
C) Formation of solids
D) Evaporation of non-volatile components
11. Which factor is most important for preventing cross-contamination when sampling different batches of solids?
A) Using the same sampling tool for all batches
B) Thoroughly cleaning and drying sampling equipment between batches
C) Sampling in a dusty environment
D) Using a large sampling container
12. What is a fundamental principle of 'random sampling'?
A) Every part of the lot has an equal chance of being selected
B) Samples are taken from specific locations
C) Samples are taken at fixed intervals
D) Samples are collected sequentially
13. In liquid sampling, what is the purpose of a 'dipper' or 'bailer'?
A) To homogenize the liquid
B) To collect a sample from a specific depth
C) To filter the liquid
D) To measure the viscosity
14. What is a significant hazard when sampling materials that can spontaneously combust?
A) Low temperature
B) Exposure to light
C) Contact with air or moisture
D) High humidity
15. Which sampling method involves taking samples at regular intervals from a moving stream of liquid?
A) Stratified sampling
B) Systematic sampling
C) Random sampling
D) Grab sampling
16. What is a key challenge in sampling gases under high vacuum?
A) Preventing leakage into the sampling system
B) Ensuring adequate flow rate
C) Cooling the gas
D) Minimizing sample volume
17. When sampling solids from bags or drums, what is a recommended practice to ensure representativeness?
A) Sample only from the top layer
B) Sample from multiple locations within the container
C) Use a single large scoop
D) Do not disturb the material
18. What is the primary hazard associated with sampling powdered materials that can become airborne?
A) Corrosion
B) Inhalation of toxic dust
C) High viscosity
D) Low vapor pressure
19. Which type of sampling is typically used for monitoring air quality over an extended period?
A) Grab sampling
B) Composite sampling
C) Stratified sampling
D) Systematic sampling
20. What does 'representativeness' of a sample mean?
A) The sample is easy to collect
B) The sample accurately reflects the composition of the bulk material
C) The sample is large enough for analysis
D) The sample is collected quickly
21. When sampling gases that are heavier than air, where is the most appropriate sampling point usually located?
A) At the top of the container
B) At the bottom of the container
C) In the middle
D) Anywhere, as gases mix readily
22. What is a critical safety consideration when sampling flammable liquids?
A) Using non-sparking tools and grounding equipment
B) Sampling in a well-ventilated area only
C) Allowing the liquid to cool before sampling
D) Using open containers
23. Which sampling principle is often employed when a large batch of solid material is known to have distinct layers or regions?
A) Simple random sampling
B) Systematic sampling
C) Stratified sampling
D) Composite sampling
24. What is the purpose of 'homogenization' in sampling?
A) To separate components
B) To make the sample uniform in composition
C) To reduce the sample size
D) To increase the analyte concentration
25. Which hazard is most associated with sampling cryogenic liquids?
A) Decomposition of the sample
B) Extreme cold causing burns or frostbite
C) High pressure buildup
D) Formation of toxic gases
26. What is the main disadvantage of using a 'grab sample' for a process that varies over time?
A) It is too difficult to collect
B) It does not represent the average composition
C) It requires too much equipment
D) It is too expensive
27. When sampling solids that can degrade upon exposure to air, what precaution is necessary?
A) Sample in a humid environment
B) Sample under an inert atmosphere
C) Sample at a higher temperature
D) Sample using a porous container
28. What is the principle behind 'systematic sampling'?
A) Taking samples at random intervals
B) Taking samples at fixed intervals of time or space
C) Taking samples from predefined zones
D) Taking a single large sample
29. Which of the following is a potential hazard when sampling highly viscous liquids?
A) Rapid evaporation
B) Difficulty in obtaining a representative sample
C) Spontaneous combustion
D) Formation of aerosols
30. The 'lot' in sampling refers to:
A) The sampling instrument
B) A specific batch or quantity of material being sampled
C) The laboratory performing the analysis
D) The method of data recording
31. What is a primary consideration for sampling gases at elevated temperatures?
A) Preventing condensation of components
B) Allowing the gas to cool to room temperature
C) Increasing the sampling pressure
D) Using a flexible sampling container
32. Which sampling method is generally preferred for large volumes of liquid in a tank or vessel?
A) Surface sampling only
B) Bottom sampling only
C) Zone or stratified sampling
D) Grab sampling from a single point
33. What is a potential hazard when sampling fine powders?
A) Risk of explosion from dust ignition
B) High viscosity
C) Formation of a solid block
D) Low vapor pressure
34. What is a 'composite sample'?
A) A single sample taken at one time
B) A sample formed by mixing multiple increments
C) A sample taken from a specific layer
D) A sample designed to be analyzed immediately
35. Which factor is LEAST important when selecting sampling equipment for solids?
A) Material compatibility with the solid
B) Ability to obtain a representative increment
C) Ease of cleaning
D) Aesthetic appearance of the equipment
36. What is meant by 'sampling error'?
A) An error in the analytical measurement
B) The difference between the sample composition and the true composition of the lot
C) An error in recording the data
D) A mistake in the calibration of instruments
37. When sampling gases from a process stream, what is a critical factor to ensure the sample is representative?
A) Sampling at ambient temperature
B) Sampling at a point of turbulent flow
C) Sampling at a low-flow rate
D) Using a large diameter sampling line
38. What is a common hazard associated with sampling corrosive liquids?
A) Inhalation of non-toxic vapors
B) Skin and eye burns
C) Low temperature effects
D) Decomposition of the sample
39. Which sampling technique is best suited for a liquid with significant stratification (e.g., density differences)?
A) Surface sampling
B) Bottom sampling
C) Zone sampling
D) Total sampling
40. What is the main objective of 'sub-sampling'?
A) To collect the entire batch
B) To reduce the bulk sample to a manageable size for analysis
C) To increase the concentration of the analyte
D) To homogenize the original material
41. In sampling liquids, 'segregation' refers to:
A) The process of filtering the liquid
B) The separation of components within the liquid
C) The method of transferring the sample
D) The rate at which the sample is taken
42. What is the primary hazard when sampling compressed gases?
A) Asphyxiation
B) Sudden release of high-pressure gas
C) Corrosion of sampling equipment
D) Formation of explosive mixtures
43. Which type of sampling is often used for large stockpiles of solid material?
A) Single point sampling
B) Composite sampling
C) Stratified sampling
D) Random sampling
44. What is a key characteristic of a 'grab sample'?
A) It is collected over a period of time
B) It represents the composition at a specific point in time and space
C) It is a mixture of several samples
D) It is used for continuous monitoring
45. When sampling solids, what is the purpose of 'increment'?
A) The total sample collected
B) A single small portion taken from a larger mass
C) The equipment used for sampling
D) The final analyzed sample
46. Which of the following is a major hazard associated with sampling volatile organic compounds (VOCs) from liquids?
A) Risk of explosion due to static discharge
B) Exposure to toxic fumes
C) Formation of precipitates
D) High viscosity of the liquid
47. What does the term 'bias' in sampling refer to?
A) The random error in the measurement
B) A systematic deviation from the true value
C) The precision of the sampling method
D) The number of replicates taken
48. When sampling gases, what is a primary concern to prevent loss of volatile components?
A) Ensuring the sampling container is at high pressure
B) Minimizing the contact time with the atmosphere
C) Allowing the gas to cool significantly before collection
D) Using a porous sampling container
49. For a liquid sample, what is a common method to avoid contamination during sampling?
A) Using a dirty sampling tool
B) Allowing the liquid to evaporate
C) Using clean, inert sampling equipment
D) Sampling from the bottom of the container only
50. Which sampling principle is most crucial for ensuring a representative sample of a heterogeneous solid mixture?
A) Random sampling
B) Stratified sampling
C) Systematic sampling
D) Composite sampling
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