A polythene piece rubbed with wool is found to have a negative change of `6.4 xx 10^(-19)C`. How many electrons have been transferred during the process?

Options

A. `4 xx 10^(12)`
B. `4 xx 10^(11)`
C. `4 `
D. None of these

Explanation

To find out how many electrons have been transferred when a polythene piece is rubbed with wool, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Charge of the Polythene Piece**:
The charge on the polythene piece is given as:
\[ Q = -6.4 \times 10^{-19} \text{ C} \]
Since the charge is negative, it indicates that electrons have been transferred to the polythene piece.

2. **Know the Charge of One Electron**:
The charge of a single electron is:
\[ e = -1.6 \times 10^{-19} \text{ C} \]
We will use the absolute value of the charge of the electron for our calculations.

3. **Use the Formula to Find the Number of Electrons Transferred**:
The number of electrons (N) transferred can be calculated using the formula:
\[ N = \frac{|Q|}{|e|} \]
Here, \(|Q|\) is the absolute value of the charge on the polythene piece, and \(|e|\) is the absolute value of the charge of one electron.

4. **Substitute the Values**:
Substitute the values into the formula:
\[ N = \frac{6.4 \times 10^{-19} \text{ C}}{1.6 \times 10^{-19} \text{ C}} \]

5. **Perform the Calculation**:
\[ N = \frac{6.4}{1.6} \times \frac{10^{-19}}{10^{-19}} = 4 \]
Therefore, the number of electrons transferred is:
\[ N = 4 \]

### Final Answer:
The number of electrons that have been transferred during the process is **4**.

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