Total electric flux coming out of a unit positive charge placed in air is

How much electric flux will come out through a surface $S = 10\hat{j}$ kept in an electrostatic field $\vec{E} = 2\hat{i} + 4\hat{j} + 7\hat{k}$ units?

The net electric flux due to a uniform electric field of $3 \times 10^3 \hat{i} \text{ NC}^{-1}$ through a cube of side $20 \text{ cm}$ oriented such that its faces are parallel to the coordinate planes is

An electric line of force in the $X, Y-$ plane is given by the equation $x^2 + y^2 = 1$. $A$ particle with unit positive charge is initially at rest at the point $(1, 0)$ in the $X, Y-$ plane. The particle:

Careful measurement of the electric field at the surface of a black box indicates that the net outward flux through the surface of the box is $8.0 \times 10^{3} \; N m^{2} / C$.
$(a)$ What is the net charge inside the box?
$(b)$ If the net outward flux through the surface of the box were zero,could you conclude that there were no charges inside the box? Why or why not?

The given figure shows the electric field lines due to two charges $q_1$ and $q_2$. What are the signs of the two charges?