If the salt bridge is removed from the two half-cells, the voltage

drops to zero

The correct answer is option 1. The voltage drops to zero.

Here is an explanation of what happens when a salt bridge is removed from an electrochemical cell:

An electrochemical cell consists of two half-cells connected by a salt bridge. Each half-cell contains an electrode and an electrolyte solution. In a galvanic (voltaic) cell, these half-cells undergo redox reactions:

Anode (Oxidation): The electrode where oxidation occurs, releasing electrons into the external circuit.

Cathode (Reduction): The electrode where reduction occurs, accepting electrons from the external circuit.

Role of the Salt Bridge

Charge Balance: The salt bridge contains an electrolyte (often a gel or solution with ions) that allows ions to migrate between the two half-cells. This migration helps balance the charge by compensating for the buildup of positive or negative charges that occur as oxidation and reduction reactions proceed.

Prevents Liquid Mixing: It prevents the direct mixing of the solutions in the two half-cells, which could otherwise lead to unwanted side reactions.

Impact of Removing the Salt Bridge

Charge Imbalance Accumulation: As the redox reactions proceed, electrons are transferred from the anode to the cathode through the external circuit. At the anode, metal atoms lose electrons and become positively charged ions, leading to an increase in positive charge in the anode compartment. At the cathode, electrons are used to reduce ions from the solution to solid metal, which can lead to an increase in negative charge in the cathode compartment.

Voltage Generation:

The voltage of the cell is driven by the difference in electrical potential between the anode and the cathode. For this voltage to be maintained, there must be a continuous flow of ions to balance the charge in each half-cell.

Removal Consequence:

When the salt bridge is removed, ion migration stops. The charge imbalance builds up rapidly because positive ions accumulate in the anode compartment and negative ions in the cathode compartment. This charge buildup creates an opposing electric field that counters the flow of electrons in the external circuit.

Resulting Effect: As the charge imbalance increases, the potential difference (voltage) between the electrodes decreases. Eventually, the voltage drops to zero because the cell can no longer sustain the flow of electrons, and the redox reactions cease.

Conclusion: The removal of the salt bridge disrupts the balance of charges between the two half-cells, halting the redox reactions and causing the cell voltage to drop to zero.