In finding the electric field using Gauss Law the formula $|\overrightarrow{\mathrm{E}}|=\frac{q_{\mathrm{enc}}}{\varepsilon_{0}|\mathrm{A}|}$ is applicable. In the formula $\varepsilon_{0}$ is permittivity of free space, $A$ is the area of Gaussian surface and $q_{enc}$ is charge enclosed by the Gaussian surface. The equation can be used in which of the following situation?

A cube of side $l$ is placed in a uniform field $E$, where $E = E\hat i$. The net electric flux through the cube is

$q_1, q_2, q_3$ and $q_4$ are point charges located at point as shown in the figure and  $S$ is a spherical Gaussian surface of radius $R$. Which of the following is true  according to the Gauss's law 

Two surfaces $S_1$ and $S_2$ are shown in figure. Flux associated with $S_1$ is ${\phi _1}$ and $S_2$ is ${\phi _2}$. Which is correct ?

A cube is placed inside an electric field, $\overrightarrow{{E}}=150\, {y}^{2}\, \hat{{j}}$. The side of the cube is $0.5 \,{m}$ and is placed in the field as shown in the given figure. The charge inside the cube is $…..\times 10^{-11} {C}$