Name the substance used in salt-bridge.

Answer

**Step-by-Step Solution:**

1. **Understanding the Purpose of a Salt Bridge:**
- A salt bridge is used in electrochemical cells to maintain electrical neutrality by allowing the flow of ions between the two half-cells.

2. **Identifying the Characteristics of the Substance:**
- The substance used in a salt bridge should be an inert electrolyte. This means it should not react chemically with the solutions in the half-cells.

3. **Examples of Suitable Substances:**
- Common examples of substances used in salt bridges include potassium chloride (KCl) and ammonium chloride (NH4Cl). These substances are chosen because they dissociate into ions in solution and do not participate in the redox reactions occurring in the cell.

4. **Conclusion:**
- Therefore, the substances commonly used in salt bridges are KCl and NH4Cl.

**Final Answer:**
- The substances used in a salt bridge are KCl (potassium chloride) and NH4Cl (ammonium chloride).

---