Give definition of electric flux.

${q_1},\;{q_2},\;{q_3}$ and ${q_4}$ are point charges located at points 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

Units of electric flux are 

An electric charge $q$ is placed at the centre of a cube of side $\alpha $. The electric flux on one of its faces will be

Give characteristics of electric field lines.

An arbitrary surface encloses a dipole. What is the electric flux through this surface ?