If charge $q$ is placed on one of the vertex of a cube, then total electric flux passing through the cube 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. . . .

$(a)$ An electrostatic field line is a continuous curve. That is,a field line cannot have sudden breaks. Why not?
$(b)$ Explain why two field lines never cross each other at any point?

$A$ few electric field lines for a system of two charges $Q_1$ and $Q_2$ fixed at two different points on the $x$-axis are shown in the figure. These lines suggest that:-

If a charge $Q$ is placed at the corner of a cube,what is the electric flux passing through one of its faces?

The figure shows the electric field lines around three point charges $A, B$,and $C$.
$(a)$ Which charges are positive?
$(b)$ Which charge has the largest magnitude? Why?
$(c)$ In which region or regions of the picture could the electric field be zero? Justify your answer.
$(i)$ Near $A$ $(ii)$ Near $B$ $(iii)$ Near $C$ $(iv)$ Nowhere