In acidic medium MnO₄^2- is converted to Mn²⁺ .The quantity of electricity in faraday required to reduce 0.5 mole of MnO₄^2- to Mn²⁺ would be :

• 2.5

• 1

• 5

• 0.5

362.

During electrolysis of water the volume of oxygen liberated is 2.24 dm³ .The volume of hydrogen liberated , under same conditions will be :

• 2.24 dm³

• 1.12 dm³

• 4.48 dm³

• 0.56 dm³

In a lead storage battery , reaction at cathode is :

• Pb + SO₄^2- $\to$ PbSO₄ + 2e^-

• Pb + PbO₂ + 2H₂SO₄ $\to$ 2PbSO₄ + 2H₂O

• PbSO₄ + 2e^- $\to$ Pb + SO₄^2-

• PbO₂ + 4H⁺ + SO₄^2- + 2e^- $\to$ PbSO₄ + 2H₂O

If hydrogen electrode dipped in two-solution of pH = 3 and pH = 6 and salt bridge is connected , the emf of resulting cell is :

• 0.177 V

• 0.3 V

• 0.052 V

• 0.104 V

If the Zn²⁺/Zn electrode is diluted to 100 times then the change in emf :

• increase of 59 mV

• decrease of 59 mV

• increase of 29.5 mV

• decrease of 29.5 mV

If equivalent conductance of 1 M benzoic acid is 12.8 ohm^-1 cm and if the conductance of benzoate ion and H⁺ ion are 42 and 288 .42 ohm^-1 cm² respectively .Its degree of dissociation is :

• 39 %

• 3.9 %

• 0.35 %

• 0.039 %

For the following concentration cell, to be spontaneous Pt(H₂)P1 atm. |HCl | Pt(H₂)P₂ atm. Which of the following is correct?

• P₁=P₂

• P₁<P₂

• P₁>P₂

• Can't be predicted

The standard oxidation potential E° for the half cell reaction are

$$\begin{gathered} \mathrm{Zn} \to {\mathrm{Zn}}^{2+} + 2{\mathrm{e}}^{-}; \mathrm{E}°= + 0.76 \mathrm{V} \\ \mathrm{Fe}\to {\mathrm{Fe}}^{2+} + 2{\mathrm{e}}^{- }; {\mathrm{E}}^{°}= + 0.41 \mathrm{V} \\ \mathrm{EMF} \mathrm{of} \mathrm{the} \mathrm{cell} \mathrm{reaction} \mathrm{is} \\ \mathrm{Zn} + {\mathrm{Fe}}^{2+} \to {\mathrm{Zn}}^{2+} + \mathrm{Fe} \end{gathered}$$

• - 0.35 V

• + 0.35 V

• 0.17V

• 1.17V.

To observe the effect of concentration on the conductivity of electrolytes of different nature were taken in two vessels A and B. A contains weak electrolyte NH₄OH and B contains strong electrolyte NaCl. In both containers, concentration of respective electrolyte was increased and conductivity observed

•  in A conductivity increases, in B conductivity decreases

• in A conductivity decreases, while in B conductivity increases

• in both A and B conductivity increase

• in both A and B conductivity decreases.

Nausadar is :

• NH₁NO₃

• NH₄Cl

• (NH₄)₂SO₄

• NH₄OH