(a) A steady current of 2 amperes was passed through two electrolytic cells X and Y connected in series containing electrolytes `FeSO_(4)` and `ZnSO_(4)` until 2.8 g of Fe deposited at the cathode of cell X. How long did the current flow ? Calculate the mass of Zn deposited at the cathode of cell Y
(Molar mass : Fe= 56 g `mol^(-1)` Zn-65.3g `mol^(-1)`, 1F -96500 C `mol^(-1)`)
(b) In the plot of molar conductivity `(wedge_(m))` vs Square root of concentration `(c^(1//2))`, following curves are obtained for two electrolytes.
A and B:
Answer the following : (i) Predict the nature of electrolytes A and B. (ii) What happens on extrapolation of `wedge_(m)` to concentration approaching zero for electrolytes A and B ?

Explanation

(a) For cell X `w=M/(nxx965000)xxIt`
`2.8=56/(2xx96500)xx2xxt`
`t=(2.8xx2xx96500)/(56xx2)=4825s`
Now, for cell Y `w=M/(nxx96500)xxIxxt`
`w=(65.3)/(2xx96500)xx4825xx2=3.625` g
(b) (i) A is the strong electrolyte.
B is the weak electrolyte
(ii) When the concentration approaching to zero strong electrolyte given `wedge_(m)^(0)` (limiting molar conductivity). But when concentration approaching to zero the curve of weak electrolyte does not cut the axis it becomes parallel to axis.