Which among the following is the $CORRECT$ formula for the determination of cell constant?

An aqueous solution of $X$ is added slowly to an aqueous solution of $Y$ as shown in List-$I$. The variation in conductivity of these reactions is given in List-$II$. Match List-$I$ with List-$II$ and select the correct answer using the code given below the lists :

List-$I$	List-$II$
$P$. $\underset{X}{(C_2H_5)_3N} + \underset{Y}{CH_3COOH}$	$1$. Conductivity decreases and then increases
$Q$. $\underset{X}{KI (0.1 \ M)} + \underset{Y}{AgNO_3 (0.01 \ M)}$	$2$. Conductivity decreases and then does not change much
$R$. $\underset{X}{CH_3COOH} + \underset{Y}{KOH}$	$3$. Conductivity increases and then does not change much
$S$. $\underset{X}{NaOH} + \underset{Y}{HI}$	$4$. Conductivity does not change much and then increases

Codes: $P \quad Q \quad R \quad S$

The limiting molar conductivities $\lambda^{0}$ for $NaCl$,$KBr$,and $KCl$ are $126$,$152$,and $150 \ S \ cm^{2} \ mol^{-1}$ respectively. What is the $\lambda^{0}$ for $NaBr$ in $S \ cm^{2} \ mol^{-1}$?

For a salt $XY$, which is a strong electrolyte, the plot of $\Lambda_m$ versus $\sqrt{C}$ has a slope of $-90.0 \ S \ cm^2 \ mol^{3/2} \ L^{1/2}$ at $298 \ K$. At $0.01 \ M$ concentration of $XY$, the value of $\Lambda_m$ is $145.5 \ S \ cm^2 \ mol^{-1}$. The limiting molar conductivity of $Y^-$ ion ($\lambda^\circ_{Y^-}$, in $S \ cm^2 \ mol^{-1}$) at $298 \ K$ will be (Given $\lambda^\circ_{X^+} = 74.0 \ S \ cm^2 \ mol^{-1}$) (in $.0$)

If the resistance of a $0.01 \, M$ electrolyte in a cell is $40 \, \Omega$ and the cell constant is $0.4 \, \text{cm}^{-1}$,what is the molar conductivity in $\Omega^{-1} \, \text{cm}^2 \, \text{mol}^{-1}$?

At a particular temperature, the ratio of equivalent conductance to specific conductance of a $0.01 \ N$ $NaCl$ solution is