Choose the incorrect statement :
(a) The electric lines of force entering into A Gaussian surface provide nagative flux.
(b) A charge 'q' is placed at the centre of a cube .The flux through all the faces will be the same .
(c ) In uniform electric field net through a closed Gaussian surface containing no net charge ,is zero .
(d) When electric field is parallel to a Gaussian surface ,it provides a finite non -zero flux. Choose the most appropriate answer from the options given below :

Options

A. (a) and (b) Only
B. (b) and (c ) Only
C. (c) only
D. (d) Only

Answer

To solve the question, we need to analyze each of the statements provided and determine which one is incorrect.

### Step-by-Step Solution:

1. **Statement (a)**: "The electric lines of force entering into a Gaussian surface provide negative flux."
- **Analysis**: The electric flux (Φ) through a surface is given by the equation:
\[ \Phi = \vec{E} \cdot \vec{A} = EA \cos \theta \]
Where \( \theta \) is the angle between the electric field vector \( \vec{E} \) and the area vector \( \vec{A} \) (which is outward for a closed surface). When electric field lines enter the Gaussian surface, \( \theta = 180^\circ \) (since the area vector points outward), and \( \cos(180^\circ) = -1 \). Therefore, the flux is negative.
- **Conclusion**: This statement is **correct**.

2. **Statement (b)**: "A charge 'q' is placed at the center of a cube. The flux through all the faces will be the same."
- **Analysis**: According to Gauss's law, the total electric flux through a closed surface is proportional to the charge enclosed. Since the charge is symmetrically placed at the center of the cube, the flux will be uniformly distributed across all six faces of the cube.
- **Conclusion**: This statement is **correct**.

3. **Statement (c)**: "In a uniform electric field, the net flux through a closed Gaussian surface containing no net charge is zero."
- **Analysis**: If there is no net charge enclosed by the Gaussian surface, according to Gauss's law, the total electric flux through that surface must be zero. This is true regardless of whether the electric field is uniform or not.
- **Conclusion**: This statement is **correct**.

4. **Statement (d)**: "When the electric field is parallel to a Gaussian surface, it provides a finite non-zero flux."
- **Analysis**: If the electric field is parallel to the surface, the angle \( \theta \) between the electric field vector and the area vector is \( 90^\circ \). Thus, \( \cos(90^\circ) = 0 \), leading to zero flux through that surface.
- **Conclusion**: This statement is **incorrect**.

### Final Answer:
The incorrect statement is **(d)**.