A standard solution of `KNO_(3)` is used to make salt bridge, because

Options

A. Velocity of `K^(+)` is greater than that of `No_(3)^(-)`
B. velocity of `No_(3)^(-)` is greater than that of `K^(+)`
C. Velocity of both `K^(+)` and `NO_(3)^(-)` are nearly the same
D. `HNO_(3)` is highly soluble in water

Explanation

The salt used to make 'salt-bridge' must be such that the ionic mobility of cation and anion are of comparable order so that they can keep the anode and cathode half cells neutral at all ti,es `KNO_3` is used because velocities of `K^(+)` and `NO_3^(-)`ions are nearly same.