Is the induced charge on the surface of a metal or inside it?

Consider a finite insulated,uncharged conductor placed near a finite positively charged conductor. The uncharged body must have a potential

$A$ and $B$ are two concentric conducting spherical shells. $A$ is given a positive charge $+Q$ while $B$ is earthed. Then:

Two charged conducting spheres $S_1$ and $S_2$ of radii $8 \text{ cm}$ and $18 \text{ cm}$ are connected to each other by a wire. After equilibrium is established, the ratio of electric fields on $S_1$ and $S_2$ spheres are $E_{S_1}$ and $E_{S_2}$ respectively. The value of $\frac{E_{S_1}}{E_{S_2}}$ is . . . . . . .

Can there be a potential difference between two adjacent conductors carrying the same charge?

‘The interior of a conductor can have no excess charge in the static situation’. Explain.