Unknown cell viewed under the microscope can be correctly concluded as a bacteria if it lacks a nucleus. Bacteria are prokaryotic organism. They do not have nuclear membrane separating their genetic material from their cytoplasm compared to eukaryotic cell such as animal cell whose genetic material is housed in a compartment with a nuclear membrane together described as nucleus.
It would be Newton's "3rd" Law that explains why my hands hurt when I clap loudly, since this states that every action as an equal and opposite reaction.
