The colour of `CuCr_2 O_7` solution in water is green because

Options

A. `Cr_2O_7^(2-)` ions are green
B. `Cu^(++)` ions are green
C. Both ions are green
D. `Cu^(++)` ions are blue and `Cr_2O_7^(2-)` ions are orange

Answer

To solve the question regarding the color of the `CuCr_2 O_7` solution in water, we can break it down into the following steps:

### Step 1: Identify the Components of `CuCr_2 O_7`
`CuCr_2 O_7` is composed of copper (Cu) and the dichromate ion (Cr2O7^2-). When dissolved in water, it dissociates into its constituent ions:
- Cu^2+ (copper ion)
- Cr2O7^2- (dichromate ion)

### Step 2: Determine the Color of Each Ion
- The copper ion (Cu^2+) is known to impart a blue color to solutions.
- The dichromate ion (Cr2O7^2-) is typically orange in color.

### Step 3: Analyze the Resulting Color
When these two ions are present together in solution, the interaction between the blue color of Cu^2+ and the orange color of Cr2O7^2- can result in a green color. This is due to the mixing of the colors, where blue and orange combine to produce green.

### Step 4: Conclusion
Thus, the color of the `CuCr_2 O_7` solution in water appears green due to the combination of the blue color from Cu^2+ and the orange color from Cr2O7^2-.

### Final Answer
The color of `CuCr_2 O_7` solution in water is green because the blue color from Cu^2+ and the orange color from Cr2O7^2- combine to produce green.

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