Which mixture(s) form(s) buffer solutions?

(P) $100 \mathrm{mL}$ of $0.200 \mathrm{M} \mathrm{HF}+ 200 \mathrm{mL}$ of$0.200 \mathrm{M} \mathrm{NaF}$

(Q)$200 \mathrm{mL}$of $0.200 \mathrm{M} \mathrm{HCl} + 200 \mathrm{mL}$ of $0.400 \mathrm{M} {\mathrm{CH}}_3{\mathrm{CO}}_2\mathrm{Na}$

(R) $300 \mathrm{mL}$ of $0.100 \mathrm{M}$ ${\mathrm{CH}}_3{\mathrm{CO}}_2\mathrm{H}+100 \mathrm{mL}$ of $0.300 \mathrm{M} {\mathrm{CH}}_3{\mathrm{CO}}_2\mathrm{Na}$