Substance `W` does not conduct electricity under any condition, `X` conducts electricity only in aqueous solution, `Y` conducts electricity in both the molten and solid states while `Z` conducts electricity in both the molten state and in aqueous solution.
Substances `W, X, Y` and `Z` could be respectively

Options

A. `HCl, S, NaCl` and `Pb`
B. `Pb, HCl, NaCl` and `S`
C. `S, HCl, Pb` and `NaCl`
D. `S, NaCl, HCl` and `Pb`

Explanation

To solve the question, we need to identify substances W, X, Y, and Z based on their electrical conductivity properties. Let's analyze each substance step by step.

### Step 1: Identify Substance W
- **Given Information**: Substance W does not conduct electricity under any condition.
- **Analysis**: The only type of substance that does not conduct electricity at all is a non-metal. Most non-metals, except for graphite, do not allow the flow of electric current.
- **Conclusion**: Substance W is a non-metal. Possible candidates include sulfur, phosphorus, etc.

### Step 2: Identify Substance X
- **Given Information**: Substance X conducts electricity only in aqueous solution.
- **Analysis**: This behavior is characteristic of acids, bases, or salts that dissociate into ions in water. A common example is hydrochloric acid (HCl), which ionizes into H⁺ and Cl⁻ ions in solution, allowing it to conduct electricity.
- **Conclusion**: Substance X is likely HCl or another acid that dissociates in water.

### Step 3: Identify Substance Y
- **Given Information**: Substance Y conducts electricity in both molten and solid states.
- **Analysis**: This property is typical of metals, as they have free-moving electrons that allow them to conduct electricity in both states. An example of such a metal is lead (Pb).
- **Conclusion**: Substance Y is a metal, such as lead (Pb).

### Step 4: Identify Substance Z
- **Given Information**: Substance Z conducts electricity in both molten state and in aqueous solution.
- **Analysis**: This behavior is also characteristic of ionic compounds, which dissociate into ions in aqueous solutions and have free ions in the molten state. Sodium chloride (NaCl) is a prime example, as it conducts electricity when dissolved in water and when melted.
- **Conclusion**: Substance Z is likely sodium chloride (NaCl).

### Final Summary
Based on the analysis:
- **Substance W**: Non-metal (e.g., Sulfur)
- **Substance X**: Acid (e.g., HCl)
- **Substance Y**: Metal (e.g., Lead, Pb)
- **Substance Z**: Ionic compound (e.g., Sodium Chloride, NaCl)

### Answer
Substances W, X, Y, and Z could be respectively: Sulfur, HCl, Lead (Pb), Sodium Chloride (NaCl).

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