Identify the set in which all the three materials are good conductors of electricity ?

Options

A. Cu,Hg and NaC
B. Cu, Ge and Hg
C. Cu, Ag and Au
D. Cu, Si and diamond

Answer

To identify the set in which all three materials are good conductors of electricity, we can analyze the given options one by one.

### Step-by-Step Solution:

1. **Examine Option A: Copper, Mercury (Hg), and Sodium Chloride (NaCl)**
- **Copper (Cu)**: A very good conductor of electricity.
- **Mercury (Hg)**: A metal that is liquid at room temperature; it is a fairly good conductor but not as good as copper.
- **Sodium Chloride (NaCl)**: An ionic compound that in solid form does not conduct electricity well. It only conducts when dissolved in water or molten.
- **Conclusion**: Not all materials are good conductors. Thus, this option is not correct.

2. **Examine Option B: Copper, Germanium (Ge), and Mercury (Hg)**
- **Copper (Cu)**: A very good conductor of electricity.
- **Germanium (Ge)**: A semiconductor, which means it is a poor conductor of electricity under normal conditions.
- **Mercury (Hg)**: A fairly good conductor but not as good as copper.
- **Conclusion**: Since germanium is a poor conductor, this option is also not correct.

3. **Examine Option C: Copper (Cu), Silver (Ag), and Gold (Au)**
- **Copper (Cu)**: A very good conductor of electricity.
- **Silver (Ag)**: The best conductor of electricity among metals.
- **Gold (Au)**: A very good conductor of electricity, though slightly less than silver.
- **Conclusion**: All three materials are excellent conductors of electricity. This option is correct.

4. **Examine Option D: Copper (Cu), Silicon (Si), and Diamond**
- **Copper (Cu)**: A very good conductor of electricity.
- **Silicon (Si)**: A semiconductor, which means it is a poor conductor of electricity under normal conditions.
- **Diamond**: An insulator, as it does not allow electricity to flow due to the absence of free electrons.
- **Conclusion**: Since silicon and diamond are not good conductors, this option is also not correct.

### Final Answer:
The correct set in which all three materials are good conductors of electricity is **Option C: Copper (Cu), Silver (Ag), and Gold (Au)**.

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