Preparation and standardization of sulphuric acid solution MCQs With Answer

Preparation and standardization of sulphuric acid solution is a core practical topic for B.Pharm students covering volumetric analysis, dilution techniques, safety, and quality control. This introduction reviews how to prepare accurate concentrations of sulphuric acid, important keywords such as normality, molarity, primary standard (e.g., anhydrous sodium carbonate), titration, and suitable indicators. You will learn correct laboratory technique: adding acid to water, using volumetric flasks and pipettes, selecting indicators like phenolphthalein, and performing calculations (N1V1 = N2V2). Emphasis on hazards, storage, and common sources of error prepares you for accurate standardization and quality assurance. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which primary standard is most commonly used to standardize sulphuric acid in the laboratory?

• Anhydrous sodium carbonate (Na2CO3)
• Potassium hydrogen phthalate (KHP)
• Sodium chloride (NaCl)
• Oxalic acid dihydrate

Correct Answer: Anhydrous sodium carbonate (Na2CO3)

Q2. When preparing a dilute solution from concentrated sulphuric acid, the safe and correct procedure is to:

• Add water slowly to the acid with stirring
• Add acid slowly to a large volume of water with stirring
• Mix acid and water in equal volumes and then dilute
• Heat the water first, then add acid quickly

Correct Answer: Add acid slowly to a large volume of water with stirring

Q3. What is the equivalent weight of sulphuric acid (H2SO4)? (Molar mass ≈ 98.08 g/mol)

• 98.08 g per equivalent
• 49.04 g per equivalent
• 24.52 g per equivalent
• 196.16 g per equivalent

Correct Answer: 49.04 g per equivalent

Q4. What is the stoichiometric mole ratio between H2SO4 and anhydrous Na2CO3 in the neutralization reaction?

• 1 mole H2SO4 reacts with 1 mole Na2CO3
• 1 mole H2SO4 reacts with 2 moles Na2CO3
• 2 moles H2SO4 react with 1 mole Na2CO3
• 1 mole H2SO4 reacts with 0.5 mole Na2CO3

Correct Answer: 1 mole H2SO4 reacts with 1 mole Na2CO3

Q5. Which indicator is most frequently used for the titration/standardization of sulphuric acid with a carbonate or strong base?

• Phenolphthalein
• Methyl orange
• Bromothymol blue
• Neutral red

Correct Answer: Phenolphthalein

Q6. Which relationship is used in volumetric acid-base titration calculations for equivalents?

• N1V1 = N2V2
• M1V1 = M2V2 (always for acids)
• N1/M1 = N2/M2
• V1/V2 = M1/M2

Correct Answer: N1V1 = N2V2

Q7. A 0.106 g sample of anhydrous Na2CO3 (M ≈ 106 g/mol) is titrated and requires 10.00 mL of sulphuric acid solution. What is the normality of the acid? (Assume 1 mol Na2CO3 = 1 mol H2SO4)

• 0.200 N
• 0.100 N
• 0.020 N
• 2.000 N

Correct Answer: 0.200 N

Q8. Which personal protective equipment (PPE) is essential when preparing concentrated sulphuric acid solutions?

• Safety goggles and acid-resistant gloves
• Lab coat
• Face shield for splashes
• All of the above

Correct Answer: All of the above

Q9. Which chemical property of concentrated sulphuric acid is responsible for charring organic material?

• Dehydrating property
• Oxidizing property only
• Reducing property
• Volatility

Correct Answer: Dehydrating property

Q10. Which volumetric glassware is most appropriate for preparing a precisely known final volume of a sulphuric acid solution?

• Volumetric flask
• Graduated cylinder
• Beaker
• Conical flask

Correct Answer: Volumetric flask

Q11. Which of the following is an advantage of using anhydrous sodium carbonate as a primary standard?

• High purity and known stoichiometry
• Relatively stable and non-volatile
• Soluble and reacts stoichiometrically with H2SO4
• All of the above

Correct Answer: All of the above

Q12. The phenolphthalein end point in an acid-base titration is observed as a change from:

• Colorless to pale pink
• Yellow to red
• Red to blue
• Blue to green

Correct Answer: Colorless to pale pink

Q13. What is the primary purpose of standardizing a prepared sulphuric acid solution?

• To determine the exact concentration for accurate quantitative analysis
• To change the physical appearance of the acid
• To remove impurities from concentrated acid
• To increase the density of the solution

Correct Answer: To determine the exact concentration for accurate quantitative analysis

Q14. The technique used to determine the concentration of an acid by reaction with a base of known concentration is called:

• Acid-base titration (volumetric analysis)
• Gravimetric analysis
• Chromatography
• Distillation

Correct Answer: Acid-base titration (volumetric analysis)

Q15. If 25.00 mL of sulphuric acid solution requires 24.50 mL of 0.100 N NaOH for neutralization, what is the normality of the sulphuric acid?

• 0.098 N
• 0.049 N
• 0.196 N
• 0.100 N

Correct Answer: 0.098 N

Q16. How should concentrated sulphuric acid be stored in the pharmacy laboratory?

• In a clearly labeled, acid-resistant container away from organic materials
• Open on a bench for easy access
• In direct sunlight on a wooden shelf
• Mixed with other acids to save space

Correct Answer: In a clearly labeled, acid-resistant container away from organic materials

Q17. During titration of Na2CO3 with H2SO4, effervescence (bubbling) is observed due to:

• Evolution of CO2 from carbonate neutralization
• Hydrogen gas formation
• Oxygen release from peroxide impurities
• Boiling caused by exothermic heat

Correct Answer: Evolution of CO2 from carbonate neutralization

Q18. What is the molarity of a 0.50 N sulphuric acid solution?

• 0.25 M
• 0.50 M
• 1.00 M
• 0.75 M

Correct Answer: 0.25 M

Q19. Which characteristic is essential for a substance to serve as a primary standard in acid-base titrations?

• High purity and chemical stability
• Volatile and decomposes easily
• Colored compound that changes color on reaction
• Highly hygroscopic so it absorbs moisture

Correct Answer: High purity and chemical stability

Q20. If the titration endpoint is consistently overshot (adding too much titrant), the calculated concentration of the analyte acid will be:

• Overestimated
• Underestimated
• Unaffected
• Exactly correct if repeated

Correct Answer: Overestimated

Q21. Why is it important to allow a volumetric flask to equilibrate to room temperature after preparing a solution and before making the final volume to the mark?

• Because solution volume changes with temperature and affects accuracy
• Because reagents must react fully for 24 hours
• Because the flask label must dry
• Because pH stabilizes only at room temperature

Correct Answer: Because solution volume changes with temperature and affects accuracy

Q22. In a titration curve for a strong acid titrated with a strong base, the steep vertical section around the equivalence point indicates:

• The equivalence point where moles of acid equivalents equal base equivalents
• A buffering region with little pH change
• Complete precipitation of a salt
• A region unsuitable for endpoint detection

Correct Answer: The equivalence point where moles of acid equivalents equal base equivalents

Q23. Why is potassium hydrogen phthalate (KHP) most commonly used to standardize sodium hydroxide rather than sulphuric acid?

• KHP is a stable, monoprotic solid acid ideal for standardizing bases like NaOH
• KHP reacts stoichiometrically with sulphuric acid only
• KHP is insoluble in water
• KHP decomposes on contact with bases

Correct Answer: KHP is a stable, monoprotic solid acid ideal for standardizing bases like NaOH

Q24. Which piece of volumetric glassware is best for transferring an accurate small aliquot of concentrated acid into a volumetric flask during preparation?

• Volumetric pipette
• Graduated cylinder
• Measuring cup
• Beaker

Correct Answer: Volumetric pipette

Q25. To prepare 250.0 mL of 0.100 N sulphuric acid from a 1.00 N stock solution, what volume of stock acid is required?

• 25.0 mL
• 2.50 mL
• 250.0 mL
• 125.0 mL

Correct Answer: 25.0 mL

Q26. Why should a burette be rinsed with the titrant before filling and titrating?

• To prevent dilution or contamination of the titrant and ensure accurate delivery
• To sterilize the burette
• To change the color of the titrant
• To heat the titrant to room temperature

Correct Answer: To prevent dilution or contamination of the titrant and ensure accurate delivery

Q27. Performing a blank titration when standardizing sulphuric acid helps to:

• Correct for interfering substances or reagent impurities
• Increase the concentration of the acid
• Reduce the volume of titrant required
• Change the pH scale used

Correct Answer: Correct for interfering substances or reagent impurities

Q28. Two distinct equivalence points are observed in the titration of a diprotic acid if:

• The pKa difference between the two protons is large enough to separate the steps
• The acid is monoprotic
• The titrant is impure
• The temperature is below freezing

Correct Answer: The pKa difference between the two protons is large enough to separate the steps

Q29. What is the molarity of a 1.00 N sulphuric acid solution?

• 0.50 M
• 1.00 M
• 2.00 M
• 0.25 M

Correct Answer: 0.50 M

Q30. If the primary standard sample used to prepare the standard solution contains inert impurities, the experimentally determined concentration of the prepared acid will be:

• Lower than the calculated value (because actual analyte amount is less)
• Higher than the calculated value
• Unaffected because impurities are inert
• Exactly the same as the theoretical value

Correct Answer: Lower than the calculated value (because actual analyte amount is less)

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com