Match List-I with List-II:

List-I (Applications)	List-II (Batteries/Cell)
(A) Transistors	(I) Anode - Zn/Hg; Cathode - HgO + C
(B) Hearing aids	(II) Hydrogen fuel cell
(C) Invertors	(III) Anode - Zn; Cathode - Carbon
(D) Apollo space ship	(IV) Anode - Pb; Cathode - Pb | PbO₂$PbO_2$

Choose the correct answer from the options given below:

Core Logic

Analyzing anodic reactions during electrolysis: * Case (A): With active Ag electrodes, silver oxidation occurs at the anode (Ag arrow Ag⁺ + e⁻$Ag \rightarrow Ag^{+} + e^{-}$). No oxygen is evolved. * Case (B): With inert Pt electrodes, oxidation of water occurs preferentially at the anode over NO₃^-$NO_3^-$ ions:2H₂O arrow O₂ + 4H⁺ + 4e⁻$$2H_2O \rightarrow O_2 + 4H^{+} + 4e^{-}$$

• Case (C): In dilute H₂SO₄$H_2SO_4$, water oxidation takes place, releasing O₂$O_2$ gas at the anode.
• Case (D): In concentrated H₂SO₄$H_2SO_4$, oxidation of SO₄²⁻$SO_4^{2-}$ creates peroxodisulphate ions (S₂O₈²⁻$S_2O_8^{2-}$), inhibiting oxygen evolution.

Pattern Recognition

Remember that active electrodes participate directly in redox reactions, whereas inert electrodes (Pt, Graphite) yield oxygen gas when water is oxidized in the presence of oxoanions like NO₃^-$NO_3^-$ or dilute SO₄²⁻$SO_4^{2-}$.

Chapter Mix

Class 12 Chemistry: Electrochemistry

Related Formula

Conductivity relationship with cell parameters:

where G^*$G^*$ represents the static cell constant.

Step 1: Setting Up Ratios

Using concentration subscripts c$c$ (concentrated) and d$d$ (dilute):

Expressing conductivity through molar conductivity values:

Substituting the graphical read coordinates (Cc = 0.15², Cd = 0.1²$C_c = 0.15^2, C_d = 0.1^2$ with scaled λm$\lambda_m$ parameters):

Pattern Recognition

Sees: Resistance correlation across specific graph coordinates. Shortcut: Equate cell parameters through κ ∝ (1)/(R)$\kappa \propto \frac{1}{R}$ and solve for the target resistance directly.

Chapter Mix

Class 12 Chemistry: Electrochemistry

Core Logic

Limiting molar conductivity relies heavily on the charge and hydrodynamic radius of the hydrated ion. Let us verify the standard experimental limiting molar ionic conductivities (λ°$\lambda^{\circ}$) at 298 K$298\text{ K}$:

• H⁺: 349.8 S cm² mol⁻¹$H^{+}: 349.8\text{ S cm}^2\text{ mol}^{-1}$ (exhibits Grotthuss proton-hopping conduction mechanism)
• Ca²⁺: 119.0 S cm² mol⁻¹$Ca^{2+}: 119.0\text{ S cm}^2\text{ mol}^{-1}$
• Mg²⁺: 106.1 S cm² mol⁻¹$Mg^{2+}: 106.1\text{ S cm}^2\text{ mol}^{-1}$
• K⁺: 73.5 S cm² mol⁻¹$K^{+}: 73.5\text{ S cm}^2\text{ mol}^{-1}$
• Na⁺: 50.1 S cm² mol⁻¹$Na^{+}: 50.1\text{ S cm}^2\text{ mol}^{-1}$

Step 1: Trend Layout

Arranging these values in descending order yields:

Pattern Recognition

Shortcut: H⁺$H^{+}$ always has the absolute highest value due to its unique proton-hopping transport system. For metal ions, a higher ionic charge boosts conductivity (M²⁺ > M⁺$M^{2+} > M^{+}$), and within a group, a smaller hydrated radius (larger bare ion) increases mobility (K⁺ > Na⁺$K^{+} > Na^{+}$).

Chapter Mix

Class 12 Chemistry: Electrochemistry

Related Formula

Core Logic

• Find the limiting molar conductance of NH₄^+$NH_4^+$ using the NH₄Cl$NH_4Cl$ data:

• Calculate Λm^°$\Lambda_m^\circ$ for the weak electrolyte ammonium hydroxide (NH₄OH$NH_4OH$):

• Evaluate the degree of dissociation (α$\alpha$):

Comparing with the format x × 10⁻¹$\mathbf{x} \times 10^{-1}$, the value of x$\mathbf{x}$ is 3.

Pattern Recognition

Kohlrausch's law allows direct algebraic recombination of ion conductances. Always construct the targeted weak base compound value by filtering out the spectator chloride contribution from the initial salt parameters.

Chapter Mix

Class 12 Chemistry: Electrochemistry