Work done in moving a positive charge on an equipotential surface is

What is the angle between an equipotential surface and electric lines of force (in $^{\circ}$)?

$A$ uniform electric field pointing in the positive $x$-direction exists in a region. Let $A$ be the origin,$B$ be the point on the $x$-axis at $x = +1 \, cm$,and $C$ be the point on the $y$-axis at $y = +1 \, cm$. Then the potentials at the points $A$,$B$,and $C$ satisfy

$A$ point charge $+q$ is placed at the origin. The work done in moving another point charge $-Q$ along the straight line path $AB$ from point $A$ with coordinates $(0, a)$ to point $B$ with coordinates $(a, 0)$ is .......

In an electric field due to charge $Q$,a charge $q$ moves from point $A$ to $B$ along an arc of a circle centered at $Q$,as shown in the figure. The work done is ($\varepsilon_0=$ permittivity of free space).

The angle between electric field lines and an equipotential surface is .........$^o$.