Is a spectral line with wavelength 656.5 nm seen in the absorption spectrum of hydrogen atoms?

Yes. Since the wavelength of the red line in the Hydrogen spectrum is 656.5 nanometer. This confirms the possibility of seeing the spectral line with the same wavelength in the absorption spectrum of hydrogen atoms. The Hydrogen spectrum has the lower limit of 656.5 nm which still includes 656.5 nm in the range. 

An  atom  (ours, not carroll's) consists of a positively charged  nucleus, surrounded by one or more negatively charged particles called  electrons. the positive charges equal the negative charges, so the atom has no overall charge; it is electrically neutral. most of an atom's mass is in its nucleus; the mass of an electron is only 1/1836 the mass of the lightest nucleus, that of hydrogen. although the nucleus is heavy, it is quite small compared with the overall size of an atom. the radius of a typical atom is around 0.1 to 0.25 nanometres (nm), whereas the radius of a nucleus is about 10-6  nm.  *  if an atom were enlarged to the size of the earth, its nucleus would be only 200 feet in diameter and could easily rest inside a small football stadium.read more on -

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