If a hole is bored along the diameter of the earth and a stone is dropped into hole

If hole is bored along the diameter of the earth and a stone is dropped into the hole then the stone

A hole is drilled along the diameter of the earth and pen is dropped into it. The time taken by it is reach other end of the earth is

If a tunnel is dug along the diameter of the earth and a ball is dropped into the tunnel, it will have

If a tunnel is dug along the diameter of earth and a piece of stone is dropped into it, then the stone will