Free Analytical Chemistry MCQs with Answers

21. Which of the following method is used to separate small molecules from the larger molecules in diffusing through a membrane?

• A. Dialysis
• B. Chromatography
• C. HPLC
• D. FPLC

Explanation: Dialysis is a separation process that uses a semipermeable membrane to separate small solute molecules from larger molecules (like proteins) in a solution based on their different rates of diffusion across the membrane.

22. Which of the following methods is chemical in nature?

• A. Acid-base titration
• B. Redox titration
• C. Precipitation titration
• D. All above methods

Explanation: All forms of titration are chemical methods of analysis because they rely on a specific chemical reaction (neutralization, oxidation-reduction, or precipitation) between the titrant and the analyte to determine the analyte's concentration.

23. Which of the following technique/method is not related to instrumental analysis?

• A. Optical method
• B. Colorimetry
• C. Polarography
• D. Gravimetric analysis

Explanation: Gravimetric analysis is a classical or "wet chemical" method that relies on the measurement of mass, typically by weighing a precipitate. Instrumental analysis involves the use of a specialized instrument to measure a physical property like light absorption or electrical potential.

24. Which of the following steps is not involved in chemical analysis?

• A. Separation of sample in pure form
• B. Separation of the sample in the mixture form
• C. Preparation of sample for the analysis
• D. Validity of experimental results

Explanation: A key step in most chemical analyses is to separate the analyte of interest from interfering substances in the mixture. Analyzing the entire mixture without separation is often not possible or accurate, making it an incorrect step in a typical analytical procedure.

25. Which of the following quantity is correct for micro analysis?

• A. 1 - 10 mg or < 50 µL
• B. 10 - 20 mg or > 50 µL
• C. 50 - 100 mg or < 100 µL
• D. 100 - 1000 mg or > 1000 µL

Explanation: Analytical methods are often classified by the size of the sample used. Microanalysis is a specific category that deals with very small sample sizes, typically in the range of 1 to 10 milligrams or less than 50 microliters.

26. Which of the following range of concentration is correct for semi-micro analysis?

• A. 10 - 1000 mg
• B. 10 - 100 mg
• C. 1 - 10 mg
• D. 20 - 1000 mg

Explanation: Semi-micro analysis is the category of chemical analysis that deals with sample sizes that are smaller than macro analysis but larger than microanalysis. The typical range for a semi-micro sample is between 10 and 100 milligrams.

27. A major constituent of material is one whose amount in the material is

• A. 1% or more
• B. 0.1%
• C. 0.01%
• D. 0.001%

Explanation: In compositional analysis, components are classified by their relative abundance. A major constituent is a component that makes up a significant portion of the total sample, conventionally defined as being present at a concentration of 1% or more.

28. A minor constituent is one whose amount in the sample is

• A. 0.1 to 1%
• B. 0.01 to 1%
• C. 1 to 10%
• D. None of above

Explanation: A minor constituent is a component that is present in a smaller amount than a major constituent but is still significant. This is typically defined as a concentration in the range of 0.01% to 1%.

29. A trace constituent is one whose amount in the sample is

• A. < 10%
• B. < 20%
• C. < 1.0%
• D. < 0.01%

Explanation: A trace constituent is a component that is present in a very small or minute amount. The conventional definition for a trace amount is a concentration of less than 100 parts per million (ppm), which is equivalent to less than 0.01%.

30. Which of the following steps is involved in quantitative analysis?

• A. Sampling
• B. Conversion of the desired constituent into a suitable form for analysis
• C. Measurement of some physical or chemical property, on which the determination is based
• D. All above steps

Explanation: A complete quantitative analysis involves multiple steps. These include obtaining a representative sample, preparing the sample for measurement (e.g., dissolving, separating), performing the measurement of a property related to the analyte, and finally, calculating and interpreting the results.