The electric field in a region is given by $\;\overrightarrow{E}=\large\frac{\in_{0} x \hat{i}}{l}\;.$ Find the charge contained inside a cubical volume bounded by the surfaces $\;x=0 , x=a , y=0 , y=a , z=0 , z=a$ where $a= 10^{-2} m$ and $l= 2 \times 10^{-2}\; m$

Question

$(a)\;22\times10^{-12}\;C\qquad(b)\;0.22\times10^{-12}\;C\qquad(c)\;2.2\times10^{-12}\;C\qquad(d)\;4.4\times10^{-12}\;C$