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JEE Main levelSingle correct optionDifficulty 2 of 3qc133

Aqueous $K X_{4} [Fe (CN) X_{6}]$ is added separately to solutions of $Cu X^{2 +}$ and $Zn X^{2 +}$ . The precipitates formed are, respectively,

Achocolate-brown $Cu X_{2} [Fe (CN) X_{6}]$ and bluish-white zinc hexacyanoferrate(II)
Bbluish-white $Cu X_{2} [Fe (CN) X_{6}]$ and chocolate-brown zinc hexacyanoferrate(II)
Cdeep blue for both
Dwhite for both

Answer: A

2 Cu X^{2 +} + [Fe (CN) X_{6}] X^{4 -} Cu X_{2} [Fe (CN) X_{6}]

is chocolate brown.

Zn X^{2 +}

gives a white to bluish-white precipitate of zinc potassium hexacyanoferrate(II). Neither ion gives the deep blue Prussian blue, which requires iron(III).

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