Electrochemistry

In an acid-base concentration cell, the current always flows from the lower concentration solution to the higher concentration solution, which in this case is the more acidic solution.

Let . Using the cell reaction and standard EMF:

In the nickel-cadmium battery, CdOH is oxidised during discharge, making it the oxidising agent.

In an electrolytic cell, the external voltage source pushes electrons into the cathode. This causes the flow of electrons to begin from the cathode and move toward the anode. Unlike galvanic cells, the electrolytic cell has a non-spontaneous reaction.

Correct cell reaction: H (g) → 2H (aq) + 2e (oxidation at anode);
Ag (aq) + e → Ag(s) (reduction at cathode)
Net reaction: None of the given options match this.

The reactivity series shows the order of metals in terms of their ability to displace other metals from solutions. The correct order is Pb

The standard EMF of the cell is: For the reaction: Using the relation:

In a sodium-sulphur battery, sodium undergoes oxidation at the anode, meaning it loses electrons to form sodium ions ( ).
The oxidation half-reaction for sodium is: Thus, the correct half-reaction for sodium in the spontaneous direction is (b).

The relationship between Gibbs free energy ( G ) and cell potential (E ) is given by: where: - = number of moles of electrons transferred, - = Faraday's constant (96,500 C/mol), - = cell potential (1.00 V), Substituting values: Using for the reaction, we get:

Ammonia ( ) acts as a base in this reaction, donating an electron pair to accept a proton (H+) from water, forming NH4+. The conjugate acid is the species formed when a base gains a proton. In this case, NH4+ is the conjugate acid of ammonia.

The total charge passed is . The number of moles of electrons is given by . For Fe to Fe , 1 mole of Fe requires 1 mole of electrons. Therefore, 0.149 mol of electrons will convert 0.149 mol of Fe to Fe . The incorrect statement is (c), as 0.075 mol of Fe remains Fe , which does not match the calculated result.