When is electric flux said to be positive,negative,or zero?

$A$ charge $Q \; \mu C$ is placed at the centre of a cube. The flux coming out from any one of its faces will be:

An electric field is uniform,and in the positive $x$ direction for positive $x,$ and uniform with the same magnitude but in the negative $x$ direction for negative $x$. It is given that $E = 200 \hat{i} \; N/C$ for $x > 0$ and $E = -200 \hat{i} \; N/C$ for $x < 0$. $A$ right circular cylinder of length $20 \; cm$ and radius $5 \; cm$ has its centre at the origin and its axis along the $x$-axis so that one face is at $x = +10 \; cm$ and the other is at $x = -10 \; cm$.
$(a)$ What is the net outward flux through each flat face?
$(b)$ What is the flux through the side of the cylinder?
$(c)$ What is the net outward flux through the cylinder?
$(d)$ What is the net charge inside the cylinder?

Consider the integral form of the Gaussian law in electrostatics: $\oint \vec{E} \cdot d\vec{s} = \frac{Q}{\epsilon_0}$. Which of the following statements are correct?

You are given a dipole of charge $+q$ and $-q$ separated by a distance $2R$. $A$ sphere '$A$' of radius ' $R$ ' passes through the centre of the dipole as shown below and another sphere '$B$' of radius ' $2R$ ' passes through the charge $+q$. Then the electric flux through the sphere '$A$' is

Consider an electric field $\vec{E} = 3 \times 10^3 \hat{i} \text{ N/C}$. What is the flux through a square of side $10 \text{ cm}$ in $Nm^2/C$ if the normal to its plane makes a $60^\circ$ angle with the $X$-axis?