Saturated solution of $KNO_3$ is used to make a salt bridge because

At $298 \ K$,the standard electrode potentials of $Cu^{2+}/Cu$,$Zn^{2+}/Zn$,$Fe^{2+}/Fe$ and $Ag^{+}/Ag$ are $0.34 \ V$,$-0.76 \ V$,$-0.44 \ V$ and $0.80 \ V$,respectively. On the basis of standard electrode potential,predict which of the following reactions cannot occur?

In a $Cu-Zn$ electrochemical cell:

At $25^{\circ} C$,the molar conductance at infinite dilution for the strong electrolytes $NaOH$,$NaCl$ and $BaCl_{2}$ are $248 \times 10^{-4}$,$126 \times 10^{-4}$ and $280 \times 10^{-4} \ S \ m^{2} \ mol^{-1}$ respectively. $\lambda_{m}^{o} Ba(OH)_{2}$ in $S \ m^{2} \ mol^{-1}$ is

Assertion : If $\lambda^o_{Na^{+}}$ and $\lambda^o_{Cl^{-}}$ are molar limiting conductivity of sodium and chloride ions respectively,then the limiting molar conductivity for sodium chloride is given by the equation :
$\Lambda^o_{NaCl} = \lambda^o_{Na^{+}} + \lambda^o_{Cl^{-}}$
Reason : This is according to Kohlrausch law of independent migration of ions.

In the cell $Zn | Zn^{2+} || Cu^{2+} | Cu$,the negative electrode is