Which species can form intermolecular hydrogen bonds with other molecules or ions of the same type?

(P) $\mathrm{HF}$  (Q) ${\mathrm{CH}}_3\mathrm{F}$ (R) ${\mathrm{NH}}_4^{+}$

${\mathrm{NH}}_4^{+}$ does not have lone pair. 
Hydrogen bonds occur when hydrogen is bonded to fluorine. So Only HF forms H-bond when the same type other molecule.0