Introduction: Understanding Types of manometers MCQs With Answer is essential for B. Pharm students studying pressure measurement in pharmaceutical processes. This concise guide covers manometer types—U-tube, differential, inclined, digital and mercury manometers—along with principles like hydrostatic pressure (p = ρgh), sensitivity, calibration, and practical applications in drug manufacturing (coating, vacuum drying, reactor pressure checks). Learn differences between manometers and other devices (Bourdon tube, barometer), safety considerations for mercury, and how to interpret readings accurately. The content is tailored for exam preparation, lab work, and concept clarity. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. What fundamental equation relates the pressure difference measured by a manometer to the fluid column height?
- p = ρgh
- p = mgh
- p = ρg/h
- p = gh/ρ
Correct Answer: p = ρgh
Q2. Which manometer is most suitable for measuring very small pressure differences with higher sensitivity?
- U-tube manometer
- Inclined manometer
- Digital pressure gauge
- Bourdon tube gauge
Correct Answer: Inclined manometer
Q3. In a U-tube manometer with mercury (ρ = 13.6 g/cm³), which property of mercury makes it commonly used?
- Low density
- High vapor pressure
- High density and low vapor pressure
- High viscosity
Correct Answer: High density and low vapor pressure
Q4. A differential manometer is primarily used to measure:
- Absolute atmospheric pressure
- Pressure difference between two points
- Temperature differences
- Mass flow rate
Correct Answer: Pressure difference between two points
Q5. For a U-tube manometer open to atmosphere on both ends, the pressure at identical fluid levels is:
- Different because of column cross-sections
- Equal regardless of fluid
- Equal only if fluids are identical and levels same
- Always zero
Correct Answer: Equal only if fluids are identical and levels same
Q6. Which manometer type reduces the visible movement of liquid per unit pressure change by using an inclined tube?
- Closed U-tube
- Inclined manometer
- Digital manometer
- Bourdon tube
Correct Answer: Inclined manometer
Q7. When using a liquid column manometer, which unit is commonly used to express small pressure differences?
- Pascal (Pa)
- Millimeter of mercury (mmHg)
- Bar
- Newton (N)
Correct Answer: Millimeter of mercury (mmHg)
Q8. What is the main safety concern when using mercury manometers in pharmaceutical labs?
- Flammability of mercury
- Mercury toxicity and contamination risk
- High electrical conductivity
- Rapid evaporation at room temperature
Correct Answer: Mercury toxicity and contamination risk
Q9. Which property of the manometric fluid increases the sensitivity of the manometer for a given pressure change?
- Higher density
- Lower density
- Higher viscosity
- Higher boiling point
Correct Answer: Lower density
Q10. In a differential manometer containing two immiscible fluids, the additional term in the pressure equation accounts for:
- Thermal expansion
- Surface tension only
- Density difference between fluids
- Electrical conductivity
Correct Answer: Density difference between fluids
Q11. For vacuum measurements near atmospheric pressure, which manometer is preferable?
- Mercury barometer
- U-tube water manometer
- Inclined manometer
- Thermocouple gauge
Correct Answer: Inclined manometer
Q12. Which instrument provides a digital readout and often replaces traditional liquid manometers for convenience?
- U-tube manometer
- Digital manometer
- Bourdon tube
- Manometric siphon
Correct Answer: Digital manometer
Q13. The hydrostatic pressure at a depth h in a fluid of density ρ is independent of:
- Depth h
- Fluid density ρ
- The shape of the container
- Gravitational acceleration g
Correct Answer: The shape of the container
Q14. In pharmaceutical coating pans, manometers are used to monitor:
- Coating thickness directly
- Air pressure and vacuum in spray systems
- Tablet hardness
- Granule moisture by spectroscopy
Correct Answer: Air pressure and vacuum in spray systems
Q15. Which of the following will cause a zero error in a U-tube manometer?
- Correct calibration
- Unequal initial levels of fluid
- Using same fluid in both limbs
- Temperature maintained constant
Correct Answer: Unequal initial levels of fluid
Q16. When converting mmH2O to Pascal, which factor is essential?
- Boiling point of water
- Density of water and gravity
- Surface tension of water
- Atmospheric composition
Correct Answer: Density of water and gravity
Q17. A micromanometer is most useful for measuring:
- Large pressures in reactors
- Very small pressure differences in HVAC and lab work
- Electrical resistance
- Temperature gradients
Correct Answer: Very small pressure differences in HVAC and lab work
Q18. Which manometer type uses a flexible element and gives readings by deflection rather than liquid displacement?
- U-tube manometer
- Bourdon tube gauge
- Inclined manometer
- Liquid differential manometer
Correct Answer: Bourdon tube gauge
Q19. In an inclined manometer, sensitivity is increased by:
- Decreasing tube inclination angle with horizontal
- Increasing fluid density
- Using a wider tube
- Raising temperature
Correct Answer: Decreasing tube inclination angle with horizontal
Q20. For measuring gas pressures in small glass reactors, which manometer fluid is often avoided due to contamination risk?
- Water
- Glycerin
- Mercury
- Synthetic oil
Correct Answer: Mercury
Q21. The reading of a simple U-tube manometer connected to a process will give gauge pressure when:
- One end is closed and evacuated
- One end open to atmosphere and other to the process
- Both ends connected to same process point
- Both ends open to atmosphere
Correct Answer: One end open to atmosphere and other to the process
Q22. In using manometers, why is temperature control important?
- Temperature only affects instrument color
- Temperature changes fluid density and vapor pressure, affecting readings
- Manometers are immune to temperature
- It changes gravitational acceleration
Correct Answer: Temperature changes fluid density and vapor pressure, affecting readings
Q23. Which fluid is commonly used in low-pressure manometers for safety and low toxicity?
- Mercury
- Water or glycerin
- Hydrochloric acid
- Liquid nitrogen
Correct Answer: Water or glycerin
Q24. A well-calibrated digital manometer offers advantages over liquid manometers by providing:
- Slower response time
- Direct numerical readout and data logging
- Higher contamination risk
- Requirement of larger volumes of fluid
Correct Answer: Direct numerical readout and data logging
Q25. In a manometer with two different fluids, the pressure at the common horizontal level is balanced by:
- Equal heights only
- Density-weighted column heights
- Surface area of columns
- Temperature difference across columns
Correct Answer: Density-weighted column heights
Q26. Which manometer configuration is used when one needs to measure pressure at two different points simultaneously?
- Single-ended barometer
- Differential manometer
- Mercury barometer
- Pitot-static tube
Correct Answer: Differential manometer
Q27. The term “zero shift” in manometers refers to:
- Permanent change in fluid density
- Change in baseline reading not due to applied pressure
- Calibration slope error
- Correct reading at zero pressure
Correct Answer: Change in baseline reading not due to applied pressure
Q28. When calculating pressure from a column of liquid in manometry, which gravitational parameter is required?
- Universal gas constant R
- Local gravitational acceleration g
- Planck constant
- Boltzmann constant
Correct Answer: Local gravitational acceleration g
Q29. For measuring pressure in a vacuum dryer used in pharmaceuticals, which manometer is impractical due to contamination risk?
- Mercury U-tube
- Capacitance manometer
- Pirani gauge
- Digital vacuum transducer
Correct Answer: Mercury U-tube
Q30. In manometry, the specific gravity of the manometric fluid is defined as:
- Density relative to air
- Density relative to water at standard conditions
- Absolute mass of fluid
- Volume per unit mass
Correct Answer: Density relative to water at standard conditions
Q31. Which phenomenon can cause capillary rise or fall and affect manometer accuracy in narrow tubes?
- Surface tension (capillarity)
- Magnetism
- Viscosity only
- Electrical charge
Correct Answer: Surface tension (capillarity)
Q32. If a manometer uses mercury and is exposed to strong heat, what primary error may arise?
- Decrease in mercury density changing readings
- Increase in tube rigidity
- Change in gravitational acceleration
- No effect at all
Correct Answer: Decrease in mercury density changing readings
Q33. A U-tube manometer shows a height difference h between limbs when connected to a process. The pressure difference Δp equals:
- ρgh/2
- ρgh
- g/ρh
- ρg/h
Correct Answer: ρgh
Q34. Which manometer type is most practical when toxic fluids like mercury cannot be used?
- Open mercury U-tube
- Electronic/digital manometer with safe sensor
- Mercury column barometer
- Chemical-filled gauge
Correct Answer: Electronic/digital manometer with safe sensor
Q35. Why would a pharmaceutical lab choose glycerin-filled manometers over water?
- Glycerin evaporates faster
- Glycerin reduces meniscus effects and evaporative loss
- Glycerin has lower density than water
- Glycerin is magnetic
Correct Answer: Glycerin reduces meniscus effects and evaporative loss
Q36. In pressure calculations involving multiple fluid layers in a manometer, what must be matched at each interface?
- Temperature only
- Pressure continuity across the interface
- Color of fluids
- Surface tension values
Correct Answer: Pressure continuity across the interface
Q37. Which device is better suited than a liquid manometer for continuous automated monitoring in production lines?
- Dipstick manometer
- Digital pressure transducer with data logging
- Large U-tube mercury manometer
- Glass thermometer
Correct Answer: Digital pressure transducer with data logging
Q38. A manometer connected between two points in a ventilation duct measures 10 mmH2O. This is primarily a measure of:
- Mass flow rate
- Static pressure difference in the duct
- Temperature difference
- Relative humidity
Correct Answer: Static pressure difference in the duct
Q39. When using an inclined manometer, the length along the tube corresponding to a small vertical height change is:
- Shorter than vertical change
- Equal to the vertical change
- Longer than the vertical change
- Unrelated to inclination
Correct Answer: Longer than the vertical change
Q40. Which calibration practice is essential for maintaining manometer accuracy in pharmaceutical labs?
- Ignoring manufacturer recommendations
- Periodic calibration against traceable standards and zero checks
- Changing fluids daily without records
- Keeping instrument unclean
Correct Answer: Periodic calibration against traceable standards and zero checks
Q41. In a liquid manometer, increasing the cross-sectional area of one limb relative to the other will:
- Have no effect on the height difference for a given pressure
- Change the scale sensitivity slightly due to displaced volume, but hydrostatic balance remains
- Reverse the pressure sign
- Eliminate surface tension forces
Correct Answer: Change the scale sensitivity slightly due to displaced volume, but hydrostatic balance remains
Q42. A mercury U-tube manometer connected to a closed vessel shows mercury displaced by 20 mm. The vessel pressure is above atmosphere by:
- 20 mmHg
- 10 mmHg
- 0 mmHg
- 40 mmHg
Correct Answer: 20 mmHg
Q43. Which factor does NOT directly influence manometer selection for a given pharmaceutical application?
- Required pressure range and sensitivity
- Compatibility of manometric fluid with process gases
- Color of the manometer frame
- Need for data logging and automation
Correct Answer: Color of the manometer frame
Q44. A differential mercury manometer uses a lighter fluid on one side to measure small differences. The liquid height difference is amplified because:
- Denser fluid reduces sensitivity
- Density contrast increases head difference for same pressure
- Surface tension dominates
- Temperature is constant
Correct Answer: Density contrast increases head difference for same pressure
Q45. What is the main limitation of using water as manometric fluid in open laboratory manometers?
- Excessive cost
- Evaporation and contamination over time
- Too high density for sensitivity
- It is magnetic
Correct Answer: Evaporation and contamination over time
Q46. In pharmaceutical scale-up, monitoring of pressure with manometers helps control:
- Active pharmaceutical ingredient (API) chemical structure
- Process conditions like vacuum, spray pressure and fluidization
- Color of tablets
- pH of solutions directly
Correct Answer: Process conditions like vacuum, spray pressure and fluidization
Q47. Which calculation step is essential when interpreting manometer readings between different fluids?
- Neglecting densities
- Converting heights using respective fluid densities to compute pressure
- Assuming equal column heights imply equal pressure always
- Using temperature only
Correct Answer: Converting heights using respective fluid densities to compute pressure
Q48. Which maintenance action helps prolong the life and accuracy of liquid manometers in the lab?
- Allowing dust and chemical vapors to accumulate
- Periodic cleaning, preventing contamination and topping up fluid
- Never checking calibration
- Storing near hot ovens
Correct Answer: Periodic cleaning, preventing contamination and topping up fluid
Q49. In a simple U-tube manometer, if both ends are connected to two process points at same pressure, the liquid levels will be:
- Different due to fluid color
- Equal because pressures are equal
- Unpredictable
- Dependent on ambient humidity
Correct Answer: Equal because pressures are equal
Q50. For highly corrosive process gases, the best manometer choice is:
- Open mercury U-tube
- Manometer with compatible fluids and corrosion-resistant wetted materials or non-contact digital sensor
- Glass water manometer with no protection
- Any manometer without consideration
Correct Answer: Manometer with compatible fluids and corrosion-resistant wetted materials or non-contact digital sensor
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