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Multiple Choice
Which of the following is the correct chemical formula for the chromate ion?
A
Cr_2O_7^{2-}
B
CrO_2^{-}
C
CrO_3^{-}
D
CrO_4^{2-}
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Verified step by step guidance
1
Understand that the problem asks for the correct chemical formula of the chromate ion, which is a polyatomic ion containing chromium and oxygen.
Recall that chromate is related to dichromate and other chromium-oxygen ions, but each has a distinct formula and charge.
Identify the formulas given: \(\mathrm{Cr_2O_7^{2-}}\) is dichromate, \(\mathrm{CrO_2^{-}}\) and \(\mathrm{CrO_3^{-}}\) are not common chromium oxyanions, and \(\mathrm{CrO_4^{2-}}\) is the chromate ion.
Recognize that the chromate ion consists of one chromium atom bonded to four oxygen atoms with an overall charge of 2-, which matches \(\mathrm{CrO_4^{2-}}\).
Conclude that the correct chemical formula for the chromate ion is \(\mathrm{CrO_4^{2-}}\) based on its composition and charge.