Which compounds contain both ionic and covalent bonds?

(P) ${\mathrm{BaSO}}_4$         (Q) $\mathrm{Ca}{\left({\mathrm{NO}}_3\right)}_2$

(R) ${\mathrm{NH}}_4\mathrm{Cl}$

 

${\mathrm{SO}}_4^{2-},{\mathrm{NO}}_3^{-},{\mathrm{NH}}_4^{+}$ contains covalent bonds. 

Covalent bonds consist of pairs of electrons shared by two atoms, and bind the atoms in a fixed orientation.