List of top Chemistry Questions on Electrochemical Cells asked in CBSE CLASS XII

Why are magnesium blocks attached to iron water pipelines?
Assertion (A): $E^\circ_{Cu^{2+}/Cu} = +0.34$ V.
Reason (R): It is due to low $\Delta H^\circ_{hyd}$ and high $\Delta H^\circ_a$.
Consider the following reaction:
$Zn_{(s)} + Ag_2O_{(s)} + H_2O_{(l)} \rightarrow Zn^{2+}_{(aq)} + 2Ag_{(s)} + 2OH^-_{(aq)}$
Given: $E^\circ_{Ag^+/Ag} = 0.80~V$, $E^\circ_{Zn^{2+}/Zn} = -0.76~V$, $1~F = 96500~C~mol^{-1}$. $\Delta_r G^\circ$ for the above reaction is:
The following reactions occur at the anode during the electrolysis of aqueous sodium chloride solution: \[ Cl^-_{(aq)} \rightarrow \frac{1}{2}Cl_2(g)+e^- \qquad E^\circ_{\text{cell}}=1.36\,V \] \[ 2H_2O(l) \rightarrow O_2(g)+4H^+(aq)+4e^- \qquad E^\circ_{\text{cell}}=1.23\,V \] Which reaction is feasible at the anode and why?
Write anode, cathode and overall reaction involved in dry cell.

The elements of the 3d transition series are given as: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn. Answer the following:

Copper has an exceptionally positive \( E^\circ_{\text{M}^{2+}/\text{M}} \) value, why?

Assertion (A): Cu cannot liberate \( H_2 \) on reaction with dilute mineral acids. 
Reason (R): Cu has positive electrode potential.