Question

part a
what is the correct formula for potassium dichromate?
○ kcr₂o₇
○ k₂cro₄
○ k₂cr₂o₇
○ k(cro₄)₂
○ none of the above

Explanation:

To determine the formula for potassium dichromate, we analyze the ions: potassium (\(K^+\)) has a +1 charge, and the dichromate ion is \(\text{Cr}_2\text{O}_7^{2-}\). To balance charges, we need 2 \(K^+\) ions for each \(\text{Cr}_2\text{O}_7^{2-}\) ion, giving the formula \(K_2\text{Cr}_2\text{O}_7\). Checking the options: \(K\text{Cr}_2\text{O}_7\) has unbalanced charge (K is +1, dichromate -2, so net -1, incorrect), \(K_2\text{CrO}_4\) is potassium chromate (not dichromate), \(K(\text{CrO}_4)_2\) is incorrect for dichromate. Thus, \(K_2\text{Cr}_2\text{O}_7\) is correct.

Answer:

C. \(K_2\text{Cr}_2\text{O}_7\) (assuming the third option is labeled C; if the original options have labels like A - E, adjust accordingly, but based on the list, the third option is \(K_2\text{Cr}_2\text{O}_7\))