We have provided 60 MCQs on Electrochemical methods of analysis, Unit-5, 1st semester, Pharmaceutical Analysis, B. Pharm.
We have covered following topics.
- Conductometry– Introduction, Conductivity cell, Conductometric titrations, applications.
- Potentiometry – Electrochemical cell, construction and working of reference (Standard hydrogen, silver chloride electrode and calomel electrode) and indicator electrodes (metal electrodes and glass electrode), methods to determine end point of potentiometric titration and applications.
- Polarography – Principle, Ilkovic equation, construction and working of dropping mercury electrode and rotating platinum electrode, applications
Table of Contents
MCQ on Electrochemical Methods of Analysis
- What is the fundamental principle of conductometry in analytical chemistry?
- A) Measurement of electrical resistance
- B) Measurement of voltage
- C) Measurement of temperature
- D) Measurement of pressure
Correct Answer: A) Measurement of electrical resistance.
2. In conductometry, what is the unit of measurement for electrical conductivity?
- A) Ohms (Ω)
- B) Volts (V)
- C) Siemens per meter (S/m)
- D) Hertz (Hz)
Correct Answer: C) Siemens per meter (S/m).
3.What is the primary purpose of a conductivity cell in conductometric measurements?
- A) To measure voltage
- B) To generate electrical resistance
- C) To measure electrical conductivity
- D) To generate electrical potential
Correct Answer: C) To measure electrical conductivity.
4.Conductometric titrations are commonly used in analytical chemistry. What is the typical property that changes during a conductometric titration?
- A) Temperature
- B) pH
- C) Electrical conductivity
- D) Optical density
Correct Answer: C) Electrical conductivity.
5.In conductometry, what type of ions conduct electrical current in solution?
- A) Anions
- B) Cations
- C) Neutrons
- D) Electrons
Correct Answer: B) Cations.
6.What is the primary function of a reference electrode in potentiometry?
- A) To measure electrical conductivity
- B) To measure voltage
- C) To maintain a constant potential
- D) To generate electrical resistance
Correct Answer: C) To maintain a constant potential.
7.In potentiometric titrations, what is the role of the indicator electrode?
- A) To maintain a constant potential
- B) To measure electrical conductivity
- C) To generate electrical resistance
- D) To sense changes in potential
Correct Answer: D) To sense changes in potential.
8.The Standard Hydrogen Electrode (SHE) is commonly used as a reference electrode. What is the electrode potential of the SHE under standard conditions?
- A) -1.23 V
- B) 0 V
- C) +1.23 V
- D) +0.0592 V
Correct Answer: B) 0 V.
9.Which electrode is typically used as the reference electrode in potentiometric measurements?
- A) Glass electrode
- B) Metal electrode
- C) Silver chloride electrode
- D) Calomel electrode
Correct Answer: D) Calomel electrode.
10.What is the purpose of a salt bridge in a potentiometric cell?
- A) To conduct electricity
- B) To maintain a constant potential
- C) To generate electrical resistance
- D) To measure electrical conductivity
Correct Answer: B) To maintain a constant potential.
11.What is the fundamental principle of polarography in electrochemical analysis?
- A) Measurement of voltage
- B) Measurement of electrical resistance
- C) Measurement of current as a function of voltage
- D) Measurement of temperature
Correct Answer: C) Measurement of current as a function of voltage.
12.What equation, developed by Ilkovic, is commonly used in polarography to describe the relationship between current and voltage?
- A) Ohm’s law
- B) Nernst equation
- C) Faraday’s law
- D) Ilkovic equation
Correct Answer: D) Ilkovic equation.
13. In polarography, what is the purpose of the dropping mercury electrode (DME)?
- A) To measure voltage
- B) To maintain a constant potential
- C) To generate electrical resistance
- D) To generate a mercury drop for the electrode
Correct Answer: D) To generate a mercury drop for the electrode.
14. What is the primary application of polarography in analytical chemistry?
- A) Determination of electrical resistance
- B) Determination of pH
- C) Determination of current-voltage relationships
- D) Determination of concentration of electroactive species
Correct Answer: D) Determination of concentration of electroactive species.
15. The rotating platinum electrode is commonly used in polarography. What advantage does it offer compared to other electrodes?
- A) It is less expensive.
- B) It is easier to maintain.
- C) It provides a larger surface area for measurements.
- D) It does not require a reference electrode.
Correct Answer: C) It provides a larger surface area for measurements.
In conductometric titrations, what property of a solution is typically monitored as the titration progresses?
- A) Color intensity
- B) pH value
- C) Electrical conductivity
- D) Refractive index
Correct Answer: C) Electrical conductivity.
Conductometry is commonly used to determine the concentration of ions in solution. What happens to the electrical conductivity as the ion concentration increases?
- A) It decreases
- B) It remains constant
- C) It increases
- D) It fluctuates randomly
Correct Answer: C) It increases.
Which type of solution would be expected to have higher electrical conductivity: a strong electrolyte solution or a weak electrolyte solution?
- A) Strong electrolyte solution
- B) Weak electrolyte solution
- C) Both have the same conductivity
- D) It depends on the temperature
Correct Answer: A) Strong electrolyte solution.
How is the electrical conductivity of a solution related to the concentration of ions?
- A) It is inversely proportional to ion concentration.
- B) It is directly proportional to ion concentration.
- C) It is unrelated to ion concentration.
- D) It is exponentially related to ion concentration.
Correct Answer: B) It is directly proportional to ion concentration.
What is the typical shape of a conductometric titration curve when plotting electrical conductivity against the volume of titrant added?
- A) Linear
- B) Parabolic
- C) Sigmoidal
- D) Exponential
Correct Answer: C) Sigmoidal.
In potentiometry, which electrode is commonly used as the reference electrode for pH measurements?
- A) Glass electrode
- B) Metal electrode
- C) Silver chloride electrode
- D) Standard hydrogen electrode
Correct Answer: A) Glass electrode.
How does a glass electrode measure pH?
- A) By generating a voltage proportional to pH
- B) By conducting electrical current through the solution
- C) By measuring the temperature of the solution
- D) By emitting light at a wavelength corresponding to pH
Correct Answer: A) By generating a voltage proportional to pH.
What is the function of the reference electrode in potentiometry?
- A) To measure pH
- B) To maintain a constant potential
- C) To generate electrical resistance
- D) To emit light for measurements
Correct Answer: B) To maintain a constant potential.
When performing a potentiometric titration, what is the endpoint of the titration determined by?
- A) A color change of the indicator
- B) The measurement of electrical conductivity
- C) A sudden change in potential
- D) The formation of a precipitate
Correct Answer: C) A sudden change in potential.
Potentiometry is often used to measure the concentration of ions in solution. Which of the following ions is commonly measured using this technique?
- A) Nitrate (NO₃⁻)
- B) Hydroxide (OH⁻)
- C) Sodium (Na⁺)
- D) Carbonate (CO₃²⁻)
Correct Answer: B) Hydroxide (OH⁻).
What is the primary advantage of using a mercury drop electrode (DME) in polarography?
- A) It requires less maintenance.
- B) It provides a larger surface area for measurements.
- C) It does not require a reference electrode.
- D) It is less expensive.
Correct Answer: B) It provides a larger surface area for measurements.
In polarography, what is the primary role of the indicator electrode?
- A) To measure voltage
- B) To maintain a constant potential
- C) To generate electrical resistance
- D) To sense changes in current
Correct Answer: D) To sense changes in current.
The Ilkovic equation is commonly used in polarography. What parameter does this equation describe?
- A) Current-voltage relationship
- B) pH measurement
- C) Temperature effect on potential
- D) Relationship between drop size and current
Correct Answer: A) Current-voltage relationship.
In polarography, the dropping mercury electrode (DME) is used to generate a mercury drop for measurements. What property of mercury makes it suitable for this purpose?
- A) High electrical conductivity
- B) Low vapor pressure
- C) Low toxicity
- D) High density
Correct Answer: B) Low vapor pressure.
What is the purpose of using a calomel electrode as a reference electrode in potentiometry?
- A) To measure the temperature of the solution
- B) To maintain a constant potential
- C) To generate electrical resistance
- D) To emit light for measurements
Correct Answer: B) To maintain a constant potential.
When using a silver chloride electrode as a reference electrode in potentiometry, what is its primary advantage?
- A) It is inexpensive and readily available.
- B) It provides a large surface area for measurements.
- C) It is resistant to corrosion.
- D) It measures electrical resistance accurately.
Correct Answer: A) It is inexpensive and readily available.
In a potentiometric titration, how is the endpoint of the titration typically detected?
- A) By measuring the change in temperature
- B) By noting a change in color of the indicator
- C) By monitoring a sudden change in potential
- D) By recording the formation of a precipitate
Correct Answer: C) By monitoring a sudden change in potential.
Potentiometry is often employed to determine the concentration of various ions in solution. Which of the following ions is commonly measured using a silver-silver chloride electrode?
- A) Sodium (Na⁺)
- B) Hydrogen (H⁺)
- C) Chloride (Cl⁻)
- D) Carbonate (CO₃²⁻)
Correct Answer: C) Chloride (Cl⁻).
What is the key advantage of using a glass electrode in potentiometric measurements for pH determination?
- A) It provides a high electrical conductivity.
- B) It is highly resistant to breakage.
- C) It can be used in a wide range of temperatures.
- D) It generates a voltage proportional to pH.
Correct Answer: D) It generates a voltage proportional to pH.
In polarography, what is the primary role of the dropping mercury electrode (DME)?
- A) To measure voltage
- B) To maintain a constant potential
- C) To generate electrical resistance
- D) To generate a mercury drop for measurements
Correct Answer: D) To generate a mercury drop for measurements.
What is the primary advantage of using a rotating platinum electrode in polarography?
- A) It is less expensive than other electrodes.
- B) It requires minimal maintenance.
- C) It provides a larger surface area for measurements.
- D) It does not require a reference electrode.
Correct Answer: C) It provides a larger surface area for measurements.
In polarography, what does the Ilkovic equation describe?
- A) The relationship between drop size and current
- B) The temperature effect on potential
- C) The pH measurement method
- D) The current-voltage relationship
Correct Answer: D) The current-voltage relationship.
Polarography is commonly used to determine the concentration of electroactive species in a solution. Which of the following is NOT an electroactive species?
- A) Oxygen (O₂)
- B) Chloride ions (Cl⁻)
- C) Sodium ions (Na⁺)
- D) Hydroxide ions (OH⁻)
Correct Answer: D) Hydroxide ions (OH⁻).
In polarography, what happens to the current as the applied voltage is increased beyond a certain point in a polarogram?
- A) It decreases linearly.
- B) It remains constant.
- C) It increases exponentially.
- D) It abruptly drops to zero.
Correct Answer: D) It abruptly drops to zero.
Polarography (Continued):
In polarography, what is the primary role of the auxiliary electrode, typically made of platinum?
- A) To generate a voltage proportional to pH
- B) To provide a reference potential
- C) To create a stable potential difference
- D) To stir the solution
Correct Answer: C) To create a stable potential difference.
The current in polarography is measured as a function of what parameter?
- A) Time
- B) Temperature
- C) Voltage
- D) Concentration
Correct Answer: C) Voltage.
What is the primary function of the dropping mercury electrode (DME) in polarography?
- A) To measure voltage
- B) To maintain a constant potential
- C) To generate electrical resistance
- D) To facilitate the formation of mercury drops
Correct Answer: D) To facilitate the formation of mercury drops.
Polarography is often used for the determination of trace metal ions in solution. Which metal ion is commonly measured using polarographic techniques?
- A) Sodium (Na⁺)
- B) Potassium (K⁺)
- C) Copper (Cu²⁺)
- D) Calcium (Ca²⁺)
Correct Answer: C) Copper (Cu²⁺).
What is the term for the graphical representation of current versus applied voltage in polarography?
- A) Polarogram
- B) Voltamogram
- C) Amperogram
- D) Conductogram
Correct Answer: A) Polarogram.
Polarographic techniques often involve the use of a mercury electrode. Why is mercury commonly used in these electrodes?
- A) It is a good conductor of electricity.
- B) It has a high melting point.
- C) It is chemically inert.
- D) It is inexpensive.
Correct Answer: C) It is chemically inert.
What is the term for the voltage at which a species undergoing reduction or oxidation in polarography begins to generate a measurable current?
- A) Half-wave potential
- B) Threshold potential
- C) Equivalence potential
- D) Saturation potential
Correct Answer: B) Threshold potential.
Polarography is often employed for the determination of oxygen concentration in various samples. What type of electrode is typically used for this purpose?
- A) Glass electrode
- B) Platinum electrode
- C) Silver electrode
- D) Clark electrode
Correct Answer: D) Clark electrode.
The application of polarography is not limited to quantitative analysis. What other type of information can be obtained from polarograms?
- A) pH of the solution
- B) Concentration of electrolytes
- C) Reaction kinetics
- D) Refractive index
Correct Answer: C) Reaction kinetics.
What is the primary advantage of polarography over other electrochemical methods in terms of sensitivity?
- A) It is less sensitive.
- B) It is equally sensitive.
- C) It is moderately sensitive.
- D) It is highly sensitive.
Correct Answer: D) It is highly sensitive.
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