Match the reagent-cation test in Column I with the observation in Column II. Column I: (P) Ba^2+ + K2CrO4 (acetic acid); (Q) Ca^2+ + (NH4)2C2O4; (R) Mg^2+ + magneson in alkali; (S) NH4+ + Nessler's reagent. Column II: (1) brown precipitate or colouration; (2) blue lake; (3) white precipitate; (4) yellow precipitate.

JEE Main levelSingle correct optionDifficulty 2 of 3qc211

Match the reagent-cation test in Column I with the observation in Column II. Column I: (P) $Ba X^{2 +}$ + $K X_{2} CrO X_{4}$ (acetic acid); (Q) $Ca X^{2 +}$ + $(NH X_{4}) X_{2} C X_{2} O X_{4}$ ; (R) $Mg X^{2 +}$ + magneson in alkali; (S) $NH X_{4} X^{+}$ + Nessler's reagent. Column II: (1) brown precipitate or colouration; (2) blue lake; (3) white precipitate; (4) yellow precipitate.

BaCrO X_{4}

is yellow (4);

CaC X_{2} O X_{4}

is white (3); magneson is adsorbed on

Mg (OH) X_{2}

giving a blue lake (2); Nessler's reagent gives brown colour or precipitate (1). Hence P-4, Q-3, R-2, S-1.