You have to design a compound microscope with objective lens of focal length 1 cm. The object should be placed at ...... distance from the lens.

A compound microscope is a combination  of two convex lenses, objective and eyepiece . In a compound microscope, the object should be placed beyond the focal length of objective lens, so that we get a magnified image of object on the other side of objective lens, which can act as an object for eyepiece lens. If we place object inside the focal length of objective lens, then we get a magnified image on the same side of objective, hence no object for eyepiece.

Now, for higher magnifying power of the telescope, the distance of the object should be small from the objective lens (more than focal length). Therefore, for an objective of focal length 1cm, object should be placed at 11 mm from the lens.