A pale-green solution gives a deep blue precipitate with K3[Fe(CN)6] and no blood-red colour with KSCN. The cation present is

JEE Main levelSingle correct optionDifficulty 2 of 3qc067

A pale-green solution gives a deep blue precipitate with $K X_{3} [Fe (CN) X_{6}]$ and no blood-red colour with $KSCN$ . The cation present is

3 Fe X^{2 +} + 2 [Fe (CN) X_{6}] X^{3 -} Fe X_{3} [Fe (CN) X_{6}] X_{2}

gives Turnbull's blue, which is specific for iron(II). Iron(III) would give blood-red colour with KSCN, and

Cr X^{3 +}

and

Ni X^{2 +}

give no deep-blue precipitate with ferricyanide.