Question

Saturated solution of $KN{O_3}$ is used to make salt bridge because:
A. velocity of ${K^ + }$ ion is greater than that of $NO_3^ -$ ion
B. velocity of $NO_3^ -$ ion is greater than that of ${K^ + }$ ion
C. velocities of both ${K^ + }$ and $NO_3^ -$ ions are nearly the same
D. $KN{O_3}$ is highly soluble in water

Answer 1

Hint: A salt bridge is a U shaped device which acts as a junction between the two half of the electrodes in the electrochemical cell. The salt bridge is a strong electrolyte so it will dissociate into its respective anion and cation which maintain the electrical neutrality of the cell.

Complete step by step answer:
A salt bridge is a device which is used in the electrochemical cell which connects the two halves of the cell which are oxidation half of the cell and reduction half of the cell.
In salt bridges commonly strong electrolytes are used which further dissociates to form ions.
The function of a salt bridge is to maintain the electrical neutrality within the circuit. If salt bridge is not used in the electrochemical cell then the negative charge will settle down in one half of the electrodes and the positive charge will settle down at the other half of the electrodes and the reaction will not occur and electricity will not be formed. For the reaction to occur smoothly and for charge transfer salt bridge is used.
For a good salt bridge the velocities of both the ions of the strong electrolyte of the salt bridge should be the same. If the velocities of the ions are the same it will not neutralize the charge of the electrodes equally. Due to difference in velocities, opposite charge is developed which will restrict the flow of charge.
For strong electrolyte $KN{O_3}$, the velocity of ${K^ + }$ and $NO_3^ -$ should be nearly the same to make a good sat bridge.
So, the correct answer is “Option C”.

Note:
The electrolyte present in the salt bridge is present in the form of gel commonly known as Agar-Agar. The concentration of salt solution and diameter of glass tube has an important role in the conductivity.