Match the cation (List I) with the reagent/observation (List II). List I: (P) $\mathrm{Ni}{}^{2+}$, (Q) $\mathrm{Co}{}^{2+}$, (R) $\mathrm{Zn}{}^{2+}$, (S) $\mathrm{Mn}{}^{2+}$. List II: (1) $\mathrm{NaBiO}{}_3$/$\mathrm{HNO}{}_3$ gives purple solution; (2) dimethylglyoxime gives red precipitate; (3) $\mathrm{K}{}_4[\mathrm{Fe}(\mathrm{CN}){}_6]$ gives white/bluish-white precipitate; (4) $\mathrm{KNO}{}_2$/acetic acid gives yellow precipitate.

1. AP-2, Q-4, R-3, S-1
2. BP-4, Q-2, R-3, S-1
3. CP-2, Q-4, R-1, S-3
4. DP-3, Q-4, R-2, S-1