Question

why microbes cannot be seen with nacked eye

Answer 1

$because \: they \: are \: very \: small \: or \: minute \: in \: size \:$

Answer 2

Those small organisms which aree not visible to naked eyes and can be seen with microscope

The tiny living organisms that cannot be seen with naked eye but can be seen under a microscope are called microorganisms or only mirobes.