Can a specimen be viewed under a microscope using the 100x objective without a coverslip?

No, a specimen should not be viewed under a microscope using the 100x objective without a coverslip. The 100x objective requires a thin layer of immersion oil to properly focus light and achieve the necessary resolution. Without a coverslip, the specimen may be too far from the lens, resulting in poor image quality and potential damage to both the specimen and the objective lens.