Proof spirit calculations MCQs With Answer

Introduction: Proof Spirit Calculations MCQs With Answer (for B. Pharm)

Proof spirit calculations are central to alcoholometry and pharmaceutical calculations in B. Pharm. You will encounter proof strength, overproof (O.P.), underproof (U.P.), rectified spirit, dilution of alcohol, specific gravity, temperature correction, hydrometers (Sikes, Gay-Lussac), and pharmacopoeial expressions like % v/v and % w/w. Knowing British proof (57.1% v/v at 51°F), American proof (2 × ABV), and conversions between proof degrees and alcohol by volume—using C1V1 = C2V2 or alcoholometric tables—is crucial for compounding tinctures, disinfectants, and spirits with regulatory accuracy. Mastering contraction on mixing, label strength, and table look-ups ensures precise, safe formulations. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. British proof spirit is defined as which strength of ethanol?

• 57.1% v/v ethanol at 51°F
• 50% v/v ethanol at 20°C
• 40% v/v ethanol at 60°F
• 95% v/v ethanol at 20°C

Correct Answer: 57.1% v/v ethanol at 51°F

Q2. In the American (U.S.) system, “proof” is defined as:

• Proof number equals twice the ABV at 60°F
• Proof number equals ABV at 20°C
• Proof number equals 1.75 × ABV
• Proof number equals density × 1000

Correct Answer: Proof number equals twice the ABV at 60°F

Q3. “Overproof” (O.P.) means:

• Strength greater than proof spirit
• Strength less than proof spirit
• Exactly equal to 100 proof
• Any spirit above 95% v/v

Correct Answer: Strength greater than proof spirit

Q4. Convert 70% v/v ethanol to British proof units (approx.):

• 22.6 O.P.
• 12.9 O.P.
• 22.6 U.P.
• 29.1 U.P.

Correct Answer: 22.6 O.P.

Q5. Convert 45% v/v ethanol to British proof units (approx.):

• 21.2 U.P.
• 21.2 O.P.
• 12.1 U.P.
• 12.1 O.P.

Correct Answer: 21.2 U.P.

Q6. Rectified spirit (pharmaceutical grade) is approximately:

• 95% v/v ethanol at 20°C
• 90% v/v ethanol at 60°F
• 100% v/v ethanol
• 70% v/v ethanol

Correct Answer: 95% v/v ethanol at 20°C

Q7. Absolute alcohol used in pharmacy is best described as:

• 99.5% v/v ethanol
• 100% w/w ethanol
• 95% w/w ethanol
• 70% v/v ethanol

Correct Answer: 99.5% v/v ethanol

Q8. The classical instrument used to determine British proof strength is:

• Sikes hydrometer
• Lactometer
• U-tube manometer
• Gas syringe

Correct Answer: Sikes hydrometer

Q9. The Gay-Lussac alcoholometer reads:

• % alcohol by volume at 15°C
• % alcohol by weight at 20°C
• British proof degrees
• Specific gravity at 4°C

Correct Answer: % alcohol by volume at 15°C

Q10. If a hydrometer reading is taken above its calibration temperature and no correction is applied, the apparent alcohol strength will be:

• Falsely high (overestimated)
• Falsely low (underestimated)
• Unaffected by temperature
• Auto-corrected by buoyancy

Correct Answer: Falsely high (overestimated)

Q11. The relation C1V1 = C2V2 is valid for alcohol dilutions when:

• Contraction is ignored and strengths are expressed as % v/v
• Only strengths are expressed in % w/w
• It is never valid for alcohol solutions
• Used exclusively with Sikes tables

Correct Answer: Contraction is ignored and strengths are expressed as % v/v

Q12. Volume of 95% v/v ethanol required to prepare 500 mL of 70% v/v (ignore contraction):

• 368.4 mL
• 350.0 mL
• 400.0 mL
• 263.2 mL

Correct Answer: 368.4 mL

Q13. Water to add to 300 mL of 90% v/v ethanol to obtain 60% v/v (ignore contraction):

• 150 mL
• 300 mL
• 50 mL
• 135 mL

Correct Answer: 150 mL

Q14. Mix 200 mL of 60% v/v with 300 mL of 95% v/v ethanol (ignore contraction). Final strength is:

• 81% v/v
• 77% v/v
• 75% v/v
• 85% v/v

Correct Answer: 81% v/v

Q15. A 40% v/v ethanol solution corresponds approximately to which British proof description?

• 30 U.P.
• 30 O.P.
• 70 O.P.
• Proof spirit

Correct Answer: 30 U.P.

Q16. A spirit labeled 25 O.P. contains approximately what % v/v ethanol?

• 71.4% v/v
• 57.1% v/v
• 45.7% v/v
• 62.5% v/v

Correct Answer: 71.4% v/v

Q17. A spirit labeled 20 U.P. contains approximately what % v/v ethanol?

• 45.7% v/v
• 37.1% v/v
• 57.1% v/v
• 70.0% v/v

Correct Answer: 45.7% v/v

Q18. In the U.S. system, a beverage with 50% ABV is:

• 100 proof
• 80 proof
• 50 proof
• 120 proof

Correct Answer: 100 proof

Q19. Which system defines proof spirit as a liquid that at 51°F weighs 12/13 of an equal volume of water?

• British proof (Sikes system)
• American proof (U.S. TTB)
• Gay-Lussac system
• OIML system

Correct Answer: British proof (Sikes system)

Q20. Alcoholometric tables are primarily used to:

• Correct hydrometer readings for temperature and convert SG to proof/ABV
• Calculate the molar mass of ethanol
• Determine the color of spirits
• Replace volumetric flasks in compounding

Correct Answer: Correct hydrometer readings for temperature and convert SG to proof/ABV

Q21. Pharmacopoeial expression for ethanol strength in formulations is typically:

• % v/v at a specified temperature (usually 20°C)
• % w/w at any temperature
• Proof degrees only
• Mole fraction

Correct Answer: % v/v at a specified temperature (usually 20°C)

Q22. “Contraction on mixing” alcohol and water refers to:

• Total volume less than the sum of component volumes
• Total volume equal to the sum
• Total volume greater than the sum
• Mass change without volume change

Correct Answer: Total volume less than the sum of component volumes

Q23. As ethanol concentration increases, the specific gravity of the mixture generally:

• Decreases
• Increases
• Remains constant
• Becomes equal to 1

Correct Answer: Decreases

Q24. To convert % w/w ethanol to % v/v, you must know the:

• Density (specific gravity) of the solution at the stated temperature
• Refractive index of water
• Boiling point of ethanol
• Flame point of the spirit

Correct Answer: Density (specific gravity) of the solution at the stated temperature

Q25. If 400 mL of 90% v/v ethanol is diluted to 600 mL, the final strength is:

• 60% v/v
• 45% v/v
• 75% v/v
• 66.7% v/v

Correct Answer: 60% v/v

Q26. How much water should be added to 750 mL of 95% v/v ethanol to obtain 70% v/v (ignore contraction)?

• 268 mL
• 214 mL
• 322 mL
• 180 mL

Correct Answer: 268 mL

Q27. Volume of 99.5% v/v ethanol needed to prepare 1 L of 90% v/v (ignore contraction):

• 904.5 mL
• 900.0 mL
• 910.0 mL
• 950.0 mL

Correct Answer: 904.5 mL

Q28. An alcoholometer calibrated at 20°C is used at 30°C without correction. The reported strength will be:

• Higher than the true strength
• Lower than the true strength
• Exactly the true strength
• Randomly variable

Correct Answer: Higher than the true strength

Q29. The quickest manual method to determine mixing ratios of two alcohols to reach a target % v/v is:

• Alligation alternate (Pearson’s square)
• Mass spectrometry
• Reflux distillation
• Potentiometry

Correct Answer: Alligation alternate (Pearson’s square)

Q30. A 70% v/v ethanol disinfectant corresponds approximately to which British proof?

• 123 proof (about 22.6 O.P.)
• 100 proof (proof spirit)
• 80 proof (20 U.P.)
• 140 proof (40 O.P.)

Correct Answer: 123 proof (about 22.6 O.P.)

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