Breathalyzer is used to detect the alcohol content in the suspected drunk drivers. The ethanol in the exhaled breath is oxidized to ethanoic acid with an acidic solution of `K_(2)Cr_(2)O_(7)` as follows `:`
`underset(Ehanol)(3CH_(3)CH_(2)OH(aq))+2Cr_(2)O_(7)^(2-)(aq) +16H^(o+)(aq) rarr underset(Ethanoic ac i d)(3CH_(3)COH(aq))+4Cr^(3+)(aq)+11H_(2)O(l)`
The breathalyzer measures the colour change and produces a metre reading calibrated in the terms of blood alcohol content.
Colour of the testing solution changes from

Options

A. Orange to green
B. Colourless to green
C. Orange to green
D. Yellow to blue

Explanation

To solve the question regarding the color change in the breathalyzer test for detecting alcohol content, we will analyze the chemical reaction involved and the associated color changes.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
The reaction involves the oxidation of ethanol (C2H5OH) to ethanoic acid (CH3COOH) in the presence of potassium dichromate (K2Cr2O7) in an acidic medium. The balanced chemical equation for the reaction is:
\[ 3C_2H_5OH(aq) + 2Cr_2O_7^{2-}(aq) + 16H^+(aq) \rightarrow 3CH_3COOH(aq) + 4Cr^{3+}(aq) + 11H_2O(l) \]

2. **Identifying the Reactants and Products**:
- **Reactants**: Ethanol (C2H5OH), potassium dichromate (K2Cr2O7), and hydrogen ions (H+).
- **Products**: Ethanoic acid (CH3COOH), chromium ions (Cr3+), and water (H2O).

3. **Color Change Observation**:
- Potassium dichromate (K2Cr2O7) is known to be orange in color due to the presence of Cr2O7^{2-} ions.
- During the reaction, Cr2O7^{2-} ions are reduced to Cr3+ ions, which are green in color.

4. **Conclusion on Color Change**:
- As ethanol is oxidized and potassium dichromate is reduced, the color of the solution changes from orange (due to Cr2O7^{2-}) to green (due to Cr3+).

5. **Final Statement**:
Therefore, the color of the testing solution changes from **orange to green**.