An electron projected with velocity v =v_0 i in the electric field...

Since, $\vec{v}=v_0 \hat{i}$ $\vec{E}=E_0 \hat{j}$ The electron is moving in $x$-direction perpendicular to the electric field which is in $y$-direction. Thus, the path of electron moving perpendicular to field will be a parabola.