What is the value of ${\mathrm{pK}}_{\mathrm{b}} ({\mathrm{CH}}_3{\mathrm{COO}}^{-} )$ if ${\mathrm{\lambda }}_{\mathrm{m}}^0= 390 \& {\mathrm{\lambda }}_{\mathrm{m}} = 7.8$ for 0.04 of a ${\mathrm{CH}}_3\mathrm{COOH}$  at $25°\mathrm{C}$ ?

(A) 9.3                                               

(B) 9.2

(C) 4.7                                               

(D) 4.8

At $25°C$, the standard emf of cell having reactions involving two electron change is found to be 0.295 V. The equilibrium constant of the reaction is-

$\left(A\right) 29.5 \times {10}^{-2}$

$\left(B\right) 10$

$\left(C\right) {10}^{10}$

$\left(D\right) 29.5 \times {10}^{10}$

The number of faradays required to produce one mole of water from a hydrogen-oxygen fuel cell containing aqueous alkali as an electrolyte is-

1. 1                               

2. 3

3. 2                               

4. 4

How much current is necessary to produce $H_2$ gas at the rate of 1 $c{m}^3$ per second under STP ?

(A) 4.305 amp                                           

(B) 17.22 amp

(C) 8.61 amp                                            

(D) 2.1525 amp.

A current of 0.250 A is passed through 400 ml of a 2.0 M solution of NaCl for 35 minutes. What will be the pH of the solution after the current is turned off ?

(A) 12.98                            

(B) 12.13

(C) 10.48                            

(D) 9.24

During discharge of a lead storage cell, the density of sulphuric acid in the cell-

1. Increases.                                     

2. Decreases.

3. Remains unchanged.                      

4. Initially increases but decreases subsequently.

The cell reaction for the given cell is spontaneous if- 

$Pt(H_2,P_1 ) H^{+} \left(1M\right) \left|\right| H^{+} \left(1M\right) | Pt(H_2, P_2 )$

$\left(A\right) P_1 > P_2$

$\left(B\right) P_1 < P_2$

$\left(C\right) P_1 = P_2$

$\left(D\right) P_2 = 1 atm$

The standard electrode potentials (reduction) of Pt/Fe³⁺, Fe²⁺ and Pt/Sn⁴⁺, Sn²⁺ are + 0.77 V and + 0.15 V respectively at 25°C. The standard EMF of the reaction Sn⁴⁺ + 2Fe²⁺ → Sn²⁺ + 2Fe³⁺ is

(A) – 0.62 V                                        

(B) – 0.92 V

(C) + 0.31 V                                        

(D) + 0.85 V

Specific conductance of 0.01 M KCl solution is x $oh{m}^{-1}c{m}^{-1}$. When conductivity cell is filled with 0.01 M KCl the conductance observed is y $oh{m}^{-1}$. When the same cell is filled with 0.01 M$H_2 S{O}_4$ the observed conductance was $z oh{m}^{-1} c{m}^{-1}.$ Hence specific conductance of 0.01 M $H_2 S{O}_4$ is-

(a) xz                                                                

(b) z/xy

(c) xz/y                                                             

(d) xy/z

$F_2$ gas can’t be obtained by the electrolysis of any $F^{-1}$salt because-

(1) Fluorine is the strongest reducing agent

(2) Fluorine is the strongest oxidising agent.

(3) Fluorine easily combine with atmospheric $O_2$

(4) All