How much work is required to move a charge $(-q)$ from point $A$ to point $C$ in the presence of a charge $+Q$ at point $B$ as shown in the figure?

$A$ hollow conducting sphere is placed in an electric field produced by a point charge at point $P$. If the electric potentials at points $A$,$B$,and $C$ are $V_A$,$V_B$,and $V_C$ respectively,as shown in the figure,then:

$A$ uniform electric field exists in the plane of the paper as shown. Here $A, B, C$, and $D$ are points on the circle. $V_{A}, V_{B}, V_{C}$, and $V_{D}$ are the potentials at those points respectively. Then:

Assertion $(A)$: In a region of constant potential,the electric field is zero and there can be no charge inside the region.
Reason $(R)$: According to Gauss's law,the charge inside the region should be zero if the electric field is zero.

Two point charges $-Q$ and $+Q / \sqrt{3}$ are placed in the $xy$-plane at the origin $(0,0)$ and a point $(2,0)$,respectively,as shown in the figure. This results in an equipotential circle of radius $R$ and potential $V = 0$ in the $xy$-plane with its center at $(b, 0)$. All lengths are measured in meters.
$(1)$ The value of $R$ is. . . . meter.
$(2)$ The value of $b$ is. . . . . .meter.

Which of the following statements is not true?