Find the number of acid(s) from the following in which $\mathrm{X}-\mathrm{H}$ bond is/are present? [X = central atom)

${\mathrm{H}}_3{\mathrm{PO}}_2,{\mathrm{H}}_5{\mathrm{P}}_3{\mathrm{O}}_{10},{\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_7,{\mathrm{H}}_3{\mathrm{PO}}_3,{\mathrm{H}}_2{\mathrm{S}}_2{\mathrm{O}}_6,{\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_5,{\mathrm{H}}_3{\mathrm{BO}}_3,{\mathrm{H}}_2{\mathrm{SO}}_4$

Due to the presence of an atom that is strongly electronegative and connected to the hydrogen atom, ${\mathrm{H}}_3{\mathrm{PO}}_2,{\mathrm{H}}_3{\mathrm{PO}}_3,{\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_5$ has an X-H bond. The degree of polarization of the molecule increases with increasing electronegativity. The electronegative atom should have a small size.