Gauss's law should be invalid if

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

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:

$A$ square Gaussian surface is placed in the $y-z$ plane. Its axis is along the $x-$axis and its center is at the origin. Two identical charges,each $Q$,are placed at points $(a, 0, 0)$ and $(-a, 0, 0)$. If each side length of the square is $2a$,then the electric flux passing through the square is:

$A$ charge $q$ is placed at the center of the circular base of an inverted cone of height $h$ and base radius $R$. The cone is capped by a hemisphere of radius $R$ as shown in the figure. The electric flux through the conical surface is $\frac{n q}{6 \epsilon_0}$ (in $SI$ units). The value of $n$ is. . . .

Which of the following is a correct statement?