Electrochemistry

Standard solution of KNO3 is used to make a salt bridge because

• Velocity of K⁺ is greater than that of NO^-3

• Velocity of NO^-3 is greater than that of K⁺.

• Velocity of both K⁺and NO^-3 are nearly same

• KNO₃ is highly soluble in water.

Which of the following assertions about the main cell is correct?

• An example of a primary cell is a mercury cell

• An example of a primary cell is a nickel-cadmium storage cell

• The electrode reactions can be reversed

• It can be recharged

Answer explanation

A primary cell is one in which the electrode reactions only happen once and cannot be reversed with electrical energy. As a result, primary cells are unable to be recharged. A main cell, such as a mercury cell, is different from a secondary cell, such as a nickel-cadmium storage cell.

• a

• b

• c

• d

Galvanised iron sheets are coated with

• Carbon

• Copper

• Zinc

• Nickel

The standard reduction potentials of X, Y, Z metals are 0.52, -3.03, -1.18 respectively. The order of reducing power of the corresponding metals is

• Y>Z>X

• X>Y>Z

• Z>Y>X

• Z>X>Y

Effect of dilution on conductivity of solution

• Increases

• Decreases

• Unchanged

• None of the above

In which of the following conditions salt bridge is not required in a galvanic cell?

• When galvanic cell is used in geyser.

• When distance between oxidation half cell and reduction half cell is negligible.

• Electrolytic solutions used in both the half cells are of same concentration.

• When both the electrodes are dipped in the same electrolytic solution.

Faraday's laws of electrolysis will fail

when

• temperature is increased

• inert electrodes are used

• a mixture of electrolytes is used

• None of these cases

Which of the following is given to a fuel cell’s cathode?

• Hydrogen

• Nitrogen

• Oxygen

• Chlorine

Answer explanation

An anode, cathode, and electrolyte membrane make up a fuel cell. In a normal fuel cell, hydrogen is passed through the anode and oxygen is passed via the cathode.

The conductivity of electrolytic conductors is due to

• Flow of free mobile electrons

• Movement of ions

• Either movement of electrons or ions

• Cannot be said

Answer explanation

The flow of free mobile electrons causes conductance in metallic conductors, while the movement of ions in a fused electrolyte solution causes conductance in electrolytic conductors.