671.

Assertion : Al becomes passive in conc. HNO_3.

Reason: Conc. HNO₄, has no action on aluminium metal.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

•  If both assertion and reason are false.

Assertion: Conductivity of all electrolytes decreases on dilution.

Reason: On dilution number of ions per unit volume decreases.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

For Zn²⁺| Zn, ${\mathrm{E}}^{\circ }$= -0.76 then EMF of the cell Zn/Zn²⁺(+1M)|2H⁺ (1M)| H₂(1 atm) will be

• -0.76 V

• 0.76 V

• 0.38 V

• -0.38 V

Electrode potential of hydrogen electrode is 18 mV, then [H⁺] is

• 0.2

• 1

• 2

• 5

Assertion : Sodiumacetate on Kolbe's electrolysis gives methane.

Reason : Methyl free radical is formed at cathode.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Assertion : Magnesium is extracted by the electrolysis of fused mixture of MgCl₂, NaCl and CaCl₂.

Reason : Calcium chloride acts as a reducing agent.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

If a salt bridge is removed between the half cells , the voltage :

• decreases to zero

• increases

• increases rapidly

• do not change

During electrochemical process :

• Gibbs free energy increases

• Gibbs free energy remains constant

• no prediction can' be made about Gibbs free energy

• Gibbs free energy decreases

A factory produces 40 kg of calcium in two hours by electrolysis. How much aluminium can be produced by same current in 2 hours if current efficiency is 50%?

• 22 kg

• 18 kg

• 9 kg

• 27 kg

The standard emf of a cell , involving one electron change is found to be 0.591 V at 25^o C . The equilibrium constant of the reaction is :

(F = 96500 C mol^-1 , R = 8.314 JK^-1mol^-1)

• 1.0 x 10¹

• 1.0 x 10⁵

• 1.0 x 10¹⁰

• 1.0 x 10³⁰