If the electric flux entering and leaving an enclosed surface respectively is ${\varphi _1}$ and ${\varphi _2}$,the electric charge inside the surface will be:

$A$ hemispherical surface of radius $a$ is placed in a uniform electric field $E$ such that the flat surface makes an angle of $\pi /4$ with the vertical. There is no charge inside the hemisphere. The electric flux passing through the curved surface of the hemisphere 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. . . .

$A$ solid uncharged conducting sphere has a radius of $3a$ and contains a hollowed spherical region of radius $2a$. $A$ point charge $+Q$ is placed at a position a distance $a$ from the common center of the spheres. What is the magnitude of the electric field at the position $r = 4a$ from the center of the spheres as marked in the figure by $P$? $\left( {k = \frac{1}{{4\pi { \in _0}}}} \right)$

$A$ large charged plane having surface charge density $4.9 \times 10^{-6} \text{ C m}^{-2}$ lies in the $x-y$ plane. $A$ circular plane of radius $1 \text{ cm}$ is lying completely in the region where $x, y$ and $z$ coordinates are all positive. When the plane's normal makes an angle $60^{\circ}$ with the $z$-axis,the electric flux through the circular plane is (Given: $\frac{1}{4 \pi \varepsilon_0} = 9 \times 10^9 \text{ N m}^2 \text{ C}^{-2}$)

Choose the correct option based on the given electric field lines diagram.