In acidic medium MO${}_4^{-}$ is converted to Mn²⁺. The quantity of electricity in faraday required to reduce 0.5 mole of MnO${}_4^{-}$ to M²⁺ would be:

• 2.5

• 5

• 1

• 0.5

222.

During electrolysis of water the volume of O₂ liberated is 2. 24dm³. The volume of hydrogen liberated, under same conditions will be

• 2.24 dm³

• 1.12 dm³

• 4.48 dm³

• 0.56 dm³

The mass of carbon anode consumed (giving only carbon dioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is (Atomic mass of Al = 27)

• 180 kg

• 270 kg

• 540 kg

• 90 kg

The best way to prevent rusting of iron is

• making it cathode

• putting in saline water

• Both (a) and (b)

• none of the above

stainless steel has iron and

• Cr

• Cu

• Co

• Zn

What flows in the internal circuit of a galvanic cell?

• ions

• electrons

• electricity

• atoms

Zinc is used to protect iron from rusting. This is because

• E${}_{\mathrm{red}}^{°}$ of Zn is greater than that of Fe

• E${}_{\mathrm{ox}}^{°}$ of Zn is greater than that of Fe

• E${}_{\mathrm{red}}^{°}$ of Zn is nearly equal to that of Fe

• Zn is cheap

The standard electrode potential (E°) for OCl^-/ Cl^- and Cl^-/ $\frac{1}{2} {\mathrm{Cl}}_2$ respectively are 0.94 V and -1.36 V. The E° value for OCl^-/ $\frac{1}{2}$Cl₂ will be

• -0.42 V

• -2.20 V

• 0.52 V

• 1.04 V

The electrolyte in lead storage battery is dilute sulphuric, acid. The concentration of sulphuric acid in a lead-storage battery must be between 4.8 M and 5.3 M for most efficient functioning. A 5 mL sulphuric acid sample of a particular battery requires 50 mL of 1.0 M NaOH for complete neutralisation. Which of the following statements about the functioning of battery is the most appropriate?

• The acid concentration in the battery is not in the most effective range

• The acid concentration in the battery is in the most effective range

• The acid concentration in the battery is hardly in the most effective range

• Only a good mechanic can tell whether or not the acid concentration in the battery is in the most effective range

In a cell that utilises the reaction

Zn (s) + 2H⁺ (aq) → Zn²⁺ + H₂ (g)

addition of H₂SO₄ to cathode compartment will

• lower the E and shift equilibrium to the left

• lower the E and shift the equilibrium to the right

• increase the E and shift the equilibrium to the right

• increase the E and shift the equilibrium to the left