In the compound K2Cr2O7, we have two potassium K ions, two chromium Cr ions, and seven oxygen O ions. To determine the oxidation state of chromium, we'll first look at the oxidation states of the other elements.Potassium K is in Group 1 of the periodic table, so it has an oxidation state of +1. Since there are two potassium ions, the total oxidation state for potassium in the compound is +2.Oxygen O typically has an oxidation state of -2. With seven oxygen ions, the total oxidation state for oxygen in the compound is -14.Now, let's denote the oxidation state of chromium as x. Since there are two chromium ions in the compound, the total oxidation state for chromium is 2x.In a neutral compound, the sum of the oxidation states of all elements must be equal to zero. Therefore, we can set up the following equation: +2 + 2x + -14 = 0Solving for x:2x = 12x = 6So, the oxidation state of chromium Cr in the compound K2Cr2O7 is +6.