Find the total number of compounds/species which have all the atoms in one plane.

${\mathrm{SOF}}_4,{\mathrm{BF}}_3,{\mathrm{CH}}_4,{\mathrm{NH}}_3,{\mathrm{CH}}_3^{\oplus }$

The B-atom in '${\mathrm{BF}}_3$' is '${\mathrm{sp}}^2$ 'hybridized with bond angle '120 degree and is triangular planar. As a result, all atoms are in the same plane. The compounds/species which have all the atoms in one plane are,

${\mathrm{BF}}^{\mathrm{\prime }},{\mathrm{CH}}_3^{+}$