Thickness of the foil of gold used in `alpha`-particle scattering experiment is

Options

A. `2.1xx10^(-7)` m
B. `3.5xx10^(-5)` m
C. `2.1xx10^(-9)` m
D. `3.5xx10^(-6)` m

Answer

To find the thickness of the gold foil used in the alpha-particle scattering experiment, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the context**: The alpha-particle scattering experiment was conducted by Rutherford to study the structure of the atom. He used a very thin foil of gold in this experiment.

2. **Know the thickness in Angstroms**: It is known that the thickness of the gold foil used in the experiment is approximately 2100 Angstroms (Å).

3. **Convert Angstroms to meters**: We need to convert the thickness from Angstroms to meters. The conversion factor is:
\[ 1 \text{ Å} = 10^{-10} \text{ m} \]
Therefore, to convert 2100 Å to meters:
\[ \text{Thickness in meters} = 2100 \text{ Å} \times 10^{-10} \text{ m/Å} \]

4. **Perform the calculation**:
\[ \text{Thickness in meters} = 2100 \times 10^{-10} \text{ m} = 2.1 \times 10^{-7} \text{ m} \]

5. **Select the correct option**: Now, we check the options given in the question:
- Option 1: \(2.1 \times 10^{-7} \text{ m}\)
- Option 2: \(3.5 \times 10^{-5} \text{ m}\)
- Option 3: \(2.1 \times 10^{-9} \text{ m}\)
- Option 4: \(3.5 \times 10^{-6} \text{ m}\)

The correct answer is **Option 1: \(2.1 \times 10^{-7} \text{ m}\)**.

### Final Answer:
The thickness of the gold foil used in the alpha-particle scattering experiment is \(2.1 \times 10^{-7} \text{ m}\).