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 transmembrane potential can be measured by ______ electrode(s).

  1. 1

  2. 2

  3. 3

  4. 4
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

To measure transmembrane potential (voltage difference across a membrane), you need two electrodes: one inside the cell and one outside in the extracellular fluid. A single electrode cannot measure a voltage difference - it requires two reference points.

Multiple choice

The resting membrane potential ranges from

  1. -40 to -90 mV

  2. 40 to 90 mV

  3. -20 to- 160 mV

  4. 20 to 160 mV
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The resting membrane potential in neurons typically falls between -40 and -90 mV, with -70 mV being the most commonly cited value. This negative charge exists because the inside of the cell is more negatively charged than the outside due to ion concentration gradients.

Multiple choice

The typical value of resting membrane potential is

  1. -50 mV
    • 60 mV
    • 70 mV
    • 80 mV
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The typical resting membrane potential for most neurons is approximately -70 mV, though this can vary between -60 and -80 mV depending on the cell type. This value represents the electrical potential difference across the cell membrane when the cell is not actively transmitting signals.

Multiple choice

Standard electrode potential values for Al3+/Al is –1.66 V and that of Tl3+/Tlis + 1.26 V. About the formation of M+/M3+ ion in solution and the electropositive character of these metals, the true statement(s) is/are A. Al and Tl form stable Al3+ and Tl3+ ions in aqueous solution. B. Tl+ is more stable than Tl3+. C. Al is more electropositive element than that of thallium.

  1. A only

  2. B only

  3. C only

  4. A and B

  5. B and C
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Standard electrode potential values for two half cell reactions suggest that aluminium has high tendency to make Al3+(aq) ions, whereas Tl3+ is not only unstable in solution but is a powerful oxidising agent also. Thus, Tl+ is more stable in solution than Tl3+. Aluminium being able to form Al3+ ions easily, is more electropositive than thallium.

Multiple choice

The surface area of each electrode helps to determine the:

  1. heating pattern

  2. current density/Concentration current

  3. amount of chemical compound

  4. healing time
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Current density is defined as the amount of current per unit area. Therefore, the surface area of the electrode directly influences how concentrated the current is at the point of contact.

Multiple choice chemistry oxidation- reduction reactions redox reactions and electrode processes redox and electrode processes applications of redox reaction

The life span of a Daniel cell may increased by:

  1. large Cu electrode
  2. lowering of CuSO$ _{4}$ concentration
  3. lowering of ZnSO$ _{4}$ concentration

  4. large zinc electrode
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In a daniel cell at anode Zn gets converted to $Zn^{2+}$
$\therefore$ If the size of electrode is increases more zinc can be oxidized,
hence the life span of the cell may be increased

Hence, option d is correct.

Multiple choice chemistry oxidation- reduction reactions redox reactions and electrode processes redox and electrode processes applications of redox reaction

Estimate the cell potential of a Daniel cell having $1.0 M - Zn^{2+}$ and originally having $ 1.0 M - Cu^{2+}$ after sufficient ammonia has been added to the cathode compartment to make the $ NH _{3}$ concentration 2.0 M. Given: $ _{zn^{2+}|Zn}^{0} = 0.76 V, E _{Cu^{2+}|Cu}^{0} = + 0.34 V, K _{f}$ for $ Cu (NH _{3}) _{4}^{2+} = 1 \times 10^{12}.$

  1. 1.10 V

  2. 0.704 V

  3. 0.396 V

  4. 1.496 V
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice chemistry oxidation- reduction reactions redox reactions and electrode processes redox and electrode processes applications of redox reaction

In a Daniel cell when $Cu$ and $Zn$ electrodes are connected current flows from:

  1. $Cu$ to $Zn$ within the cell
  2. $Cu$ to $Zn$ outside the cell
  3. $Zn$ to $Cu$ outside the cell

  4. all of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
We know outside the cell, electron flow from anode to cathode in the external current. Chemical energy is converted into electrical energy. The net reaction is the sum of two half-cell reactions.

For daniel cell, $Zn$ is at the anode and $Cu$ at the cathode.
The electron current flows from Zn to Cu.

So, the correct option is ( C )
Multiple choice chemistry oxidation- reduction reactions redox reactions and electrode processes redox and electrode processes applications of redox reaction

In the electrochemical cell $H _{2}(g),1atm|H^{+}(1M)||Cu^{2+}(1M)|Cu(s)$, which one of the following statements is true? 

  1. H$ _{2}$ is cathode, Cu is anode

  2. Oxidation occurs at Cu electrode
  3. Reduction occurs at H$ _{2}$ electrode
  4. H$ _{2}$ is anode, Cu is Cathode
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

At anode oxidation takes place and at cathode reduction take place
$\therefore H _2$ is anode and Cu is cathode

Multiple choice chemistry oxidation- reduction reactions redox reactions and electrode processes redox and electrode processes applications of redox reaction

The standard EMF of a Daniel cell at 298 K is $E _{1}$. When the concentration of $ZnSO _{4}$ is 1.0 M and that of $CuSO _{4}$ is 0.01 M, the EMF becomes $E _{2}$ at 298 K. The correct relationship between $E _{1}$ and $E _{2}$ is

  1. $E _{1} = E _{2}$
  2. $E _{2}=0$
  3. $E _{1} > E _{2}$
  4. $E _{1} < E _{2}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

According to the Nernst equation, E = E0 - (0.059/2) * log([Zn2+]/[Cu2+]). As [Cu2+] decreases from 1.0 M to 0.01 M, the log term increases, making the subtraction larger and thus E2 < E1.

Multiple choice chemistry oxidation- reduction reactions redox reactions and electrode processes redox and electrode processes applications of redox reaction

If a current of 1.0 A is drawn from the Daniel cell for 96.5 min, the cathode will gain in weight by (Cu = 63.5, Zn = 65.4)

  1. 1.905 g

  2. 1.962 g

  3. 3.81 g

  4. 3.924 g
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Using Faraday's law of electrolysis: mass = (I * t * M) / (n * F). I = 1.0 A, t = 96.5 * 60 seconds = 5790 s, M = 63.5, n = 2, F = 96500 C/mol. Mass = (1 * 5790 * 63.5) / (2 * 96500) = 1.905 g.

Multiple choice chemistry oxidation- reduction reactions redox reactions and electrode processes redox and electrode processes applications of redox reaction

Electrochemical Battery

An electrochemical battery is a device powered by oxidation and reduction reactions that are physically separated. So that the electrons must travel through a wire from the reducing agent to the oxidizing agent. 

The reducing agent loses electrons and is oxidized in a reaction that takes place at an electrode is called the anode. The oxidizing agent gains electrons and is reduced in a reaction that takes at an electrode is called the cathode.  

To maintain a net zero charge in each compartment, there is a limited flow of ions through a salt bridge. 
For example, in a car battery the reducing agent is oxidized by the following reaction, which involves a lead ( $Pb$ ) anode and sulfuric acid ( $H _2SO _4$). Lead sulfate ( $PbSO _4$ ), protons ( $H$ ), and electrons ( $e^-$) are produced.

At the cathode, the below reaction occurs :

$PbO _2+H _2SO _4+2H^++2e^-\rightarrow$ PbSO_4+2H_2O$
 
At the anode, the below reaction occurs :

$Pb+H_2SO_4 \rightarrow PbSO_4+2H^++2e^-$

Electrons are produced by a chemical reaction that takes place at the:

  1. anode.

  2. cathode.

  3. lead oxide electrode.

  4. oxidizer.

  5. salt bridge.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

At the anode, oxidation of metal takes place;

oxidation is the process of removal of the electron;

So, the electrons that are produced in the chemical reaction take place at the anode.

Hence, option (A) is correct