50 " mL of " an acidic solution of 0.255 M `K_2Cr_2O_7`, 30 " mL of " 0.4 M `K_2C_2O_4`, and 120 " mL of " 0.2 M `Fe^(2+)` are added together. Compute the molarities of `Fe^(3+)` ions and `Cr_2O_7^(2-)` ions in the final solution.

Explanation

To solve the problem, we need to calculate the molarities of `Fe^(3+)` ions and `Cr_2O_7^(2-)` ions in the final solution after mixing the three solutions.

### Step-by-Step Solution:

1. **Calculate the number of equivalents of `K_2Cr_2O_7`:**
- Molarity (M) = 0.255 M
- Volume (V) = 50 mL = 0.050 L
- Change in oxidation state for `K_2Cr_2O_7` is 6 (from Cr(VI) to Cr(III)).
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