Which of these liquids will light up an LED connected in a tester circuit?

Options

A. Honey
B. Vinegar
C. Milk
D. Oil

Answer

To determine which of the given liquids will light up an LED connected in a tester circuit, we need to analyze the properties of the liquids in question. Here's a step-by-step solution:

### Step 1: Understand the Tester Circuit
A tester circuit consists of a container filled with a liquid and two conductive rods dipped into that liquid. The circuit is completed when the liquid allows electric current to flow between the rods, lighting up the LED.

**Hint:** Remember that for the LED to light up, the circuit must be complete, meaning current must flow through the liquid.

### Step 2: Identify the Requirement for Current Flow
For current to flow through the liquid, it must contain charged particles (ions). These ions can be either cations (positively charged) or anions (negatively charged). Liquids that can dissociate into ions when dissolved in water are called electrolytes.

**Hint:** Think about what types of liquids can conduct electricity. What do they need to have?

### Step 3: Analyze the Given Liquids
Let’s consider the options:
1. **Vinegar (Acetic Acid)**: This is an acid that dissociates into acetate ions (CH3COO-) and hydrogen ions (H+), making it an electrolyte.
2. **Honey**: Honey is a viscous liquid that does not dissociate into ions and is not a good conductor of electricity.
3. **Milk**: While milk contains some ions, it is not a strong electrolyte and does not conduct electricity well enough to light an LED.
4. **Oil**: Oil is a non-polar substance and does not conduct electricity as it does not contain ions.

**Hint:** Consider which of these liquids can break down into ions when an electric current is applied.

### Step 4: Conclusion
Among the given options, only vinegar (acetic acid) can dissociate into ions and allow electric current to flow. Therefore, it is the only liquid that will light up the LED in the tester circuit.

**Final Answer:** The liquid that will light up the LED is **Vinegar (Acetic Acid)**.