Which of the following statements about the chromyl chloride test are correct?

AChromium has the oxidation state +6 in both $K X_{2} Cr X_{2} O X_{7}$ and $CrO X_{2} Cl X_{2}$ .
BThe test is not given by $HgCl X_{2}$ because it is covalent and does not release free chloride ions.
C $CrO X_{2} Cl X_{2}$ has a tetrahedral molecular geometry.
DThe test works equally well if the solid dichromate is replaced by dilute $H X_{2} SO X_{4}$ only.

Answer: A, B, C

Both Cr atoms are +6 in

K X_{2} Cr X_{2} O X_{7}

and in

CrO X_{2} Cl X_{2}

, so 1 is true. Covalent

HgCl X_{2}

gives no free

Cl X^{-}

, so 2 is true. The molecule is tetrahedral (Cr with two oxo and two chloro ligands), so 3 is true. Statement 4 is false: solid dichromate and concentrated acid are both needed.

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Which of the following statements about the chromyl chloride test are correct?

Answer: A, B, C

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