Chemistry · Physics

Electrochemistry and Current Electricity

224 Questions

Review fundamental concepts of electrochemistry and current electricity through these practice questions. The set includes numerical problems on electrolysis, drift velocity, and electrode potentials. These topics frequently appear in engineering, CSIR NET, and state PSC prelims examinations for thorough preparation.

Electrolysis calculationsElectrode potentialNernst equationDrift velocityFuel cellsMolar conductivity

Electrochemistry and Current Electricity Questions

Multiple choice

The Kolbe's electrolytic method is introduced by using

  1. CH3COONa and H2O

  2. R2CuLi and RX

  3. CH3CHO and NH2NH2

  4. RX and Zn

  5. RCOOAg and I2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct. In the electrolysis of the concentrated aqeuous solution of alkali salt of the saturated monocarboxylic acid using Pt electrode, alkane is collected at anode, while the strong base is collected at cathode.

Multiple choice

A cell has O.P. = 24 atm, T.P. = 10 atm at a particular time. Water potential of that cell at that time will be
    • 10 bars

  2. 0 bar
    • 10 bars
    • 14 bars
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Water potential (ψ) is the sum of osmotic potential (ψs) and turgor pressure (ψp). Given OP = 24 atm (ψs = -24 atm) and TP = 10 atm (ψp = +10 atm), water potential = -24 + 10 = -14 atm. Since 1 atm ≈ 1.013 bar, -14 atm ≈ -14.2 bars, making -14 bars the closest answer.

Multiple choice

Which of the following statements is true about passage of electric current through a copper sulphate solution?

  1. When electric current is passed through the copper sulphate solution, the copper sulphate does not dissociate.

  2. The free copper gets drawn to the electrode connected to the negative terminal of the battery.

  3. The free copper gets drawn to the electrode connected to the positive terminal of the battery.

  4. The mass of copper that gets deposited on one electrode is more than the mass of copper that gets depleted from the other electrode.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When electric current is passed through the copper sulphate solution, the copper sulphate does not dissociate.

Multiple choice

A 1 kg carbon rod was connected to the negative terminal of a battery. A 2 kg copper rod was connected to the positive terminal. Both were dipped in an aqueous solution of copper sulphate and a current was passed for 15 minutes. Which of the following cannot be the mass of the carbon rod after this time?

  1. 1 kg

  2. 2 kg

  3. 2.5 kg

  4. 3 kg
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Some of the copper from the copper rod gets deposited on the carbon rod. Hence, the mass of the carbon rod increases. Hence, its mass must be more than 1 kg. Hence, option (1) is not feasible.

Multiple choice

Which of the following would result in dissolution of copper from one electrode and deposition of it on the other?

  1. Copper plate connected to the positive terminal, carbon rod connected to the negative terminal, and copper sulphate as the solution

  2. Carbon rod connected to the negative terminal, copper plate connected to the positive terminal, and copper sulphate as the solution

  3. Carbon rod connected to the negative terminal, copper plate connected to the positive terminal and an aqueous solution of sulphuric acid as the solution

  4. Carbon rod connected to the postive terminal of the battery, copper plate connected to the negative terminal of the body, and copper sulphate as the solution

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Only in option (2) will the desired effect be reached.

Multiple choice

Which of the following electrodes has a stable and well-known electrode potential?

  1. The Auxiliary electrode

  2. A reference electrode

  3. The Clark electrode

  4. A carbon-paste electrode
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A reference electrode is an electrode which has a stable and well-known electrode potential. The high stability of the electrode potential is usually reached by employing a redox system with constant (buffered or saturated) concentrations of each participants of the redox reaction.

Multiple choice

Among the following electrodes which one is a type of redox electrode?

  1. Palladium-hydrogen electrode

  2. Plate electrode

  3. Quinhydrone electrode

  4. Potassium selective electrodes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The quinhydrone electrode is a type of redox electrode which can be used to measure the hydrogen ion concentration (pH) of a solution in a chemical experiment. It provides an alternative to the commonly used glass electrode in a pH meter. The electrode consists of an inert metal electrode (usually a platinum wire) in contact with quinhydrone crystals and a water-based solution.

Multiple choice

Hydrodynamic voltammetry is an electrochemical technique in which a faradaic current passing through the electrolysis solution is measured while an appropriate potential is applied to the polarizable or indicator electrode.The electrode used in this process is

  1. a reference electrode

  2. a reversible hydrogen electrode

  3. a rotating disk electrode

  4. a rotating ring-disk electrode
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A rotating ring-disk electrode (RRDE) is double working electrode used in hydrodynamic voltammetry, very similar to a rotating disk electrode (RDE). The electrode actually rotates during experiments inducing a flux of analyte to the electrode. These working electrode are used in electrochemical studies when investigating reaction mechanisms related to redox chemistry among other chemical phenomenon.

Multiple choice

The minimum number of cells required to make a battery is

  1. 1

  2. 2

  3. 4

  4. 6

  5. 10
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Yes, battery is a combination of cells connected together. The positive terminal of one cell is connected to the negative terminal of the next cell. The minimum number of cells needed to make a battery is 2.

Multiple choice

Which of the following statements is correct?

  1. The reference calomel electrode is made from HgCl2.

  2. Electrolysis involves oxidation and reduction at cathode and anode respectively.

  3. The standard electrode potential is measured by galvanometer.

  4. If a salt bridge is removed between the two half cells, the voltage will drop to zero.

  5. In electroplating, the article to be electroplated serves as a cathode.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This statement is correct. If a salt bridge is removed between the two half cells, the voltage will drop to zero.

Multiple choice

Calculate the minimum concentration of Ag+ that would remain unreduced by a standard Fe2+/Fe3+ electrodes at equilibrium?

Given Fe3+ + e- → Fe2+ + 0.671 v Ag+ + e- → Ag + 0.699 v

  1. 0.335 M

  2. 0.435 M

  3. 0.235 M

  4. 0.135 M

  5. 0.535 M
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The cell reaction is Fe2+ (aq) + Ag+ (aq) → Fe3+ (aq) + Ag (s)Eo cell = Eo Fe2+ → Fe3+ + E Ag+ → Ag (s)Eo cell = (- 671) + (0.699)Eo cell = + 0.028 vEo cell = 0.059/n log (Fe3+ x Ag)/(Fe2+ x [Ag+]) Now Eo cell = 0.028 vn = 1, [Fe3+] = [ Fe2+] = 1 M, [Ag+] = ? 0.028 = 0.059/1 log (1 x 1)/(1 x [Ag + ]) 0.028/0.059 = log 1/([Ag+])log 1/([Ag+]) = 0.4745log 1/([Ag+]) = 100.4745 = 2.98 [Ag+] = 1/2.98 = 0.335 M.

Multiple choice

Which of the following statements are false?

A. If a salt bridge is removed between the two half cells, the voltage will drop to zero. B. In electroplating the article to be electroplated serves as cathode. C. The reference calomel electrode is made from Hg2Cl2. D. Electrolysis involves oxidation and reduction respectively at cathode and anode.

  1. A and B

  2. A and D

  3. B and C

  4. B and D

  5. A and C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Both are false. In electroplating the article to be electroplated serves as anode and electrolysis involves oxidation and reduction respectively at anode and cathode.