What is the oxidation state of chromium (Cr) in K2Cr2O7?

• A. +2
• B. +6
• C. +7
• D. +3

Answer: (B)

Verified step by step guidance

1. Identify the overall charge of the compound K2Cr2O7, which is neutral (0).
2. Assign the known oxidation states: potassium (K) is always +1, and oxygen (O) is usually -2.
3. Set up an equation to represent the sum of oxidation states: 2(K) + 2(Cr) + 7(O) = 0, where K = +1 and O = -2.
4. Substitute the known values into the equation: 2(+1) + 2(x) + 7(-2) = 0, where x is the oxidation state of chromium.
5. Solve the equation for x to find the oxidation state of chromium in K2Cr2O7.