For the reaction `NO_(2)+COrarrCO_(2)+NO`, the experimental rate expresison is `-dc//dt = k[NO_(2)]^(2)`. Find the number of molecules of `CO` involved in the slowest step.

Answer

To solve the problem, we need to analyze the given reaction and the provided rate expression.

### Step-by-Step Solution:

1. **Identify the Reaction**: The reaction given is:
\[ \text{NO}_2 + \text{CO} \rightarrow \text{CO}_2 + \text{NO} \]

2. **Understand the Rate Expression**: The experimental rate expression is given as:
\[ -\frac{dC}{dt} = k[\text{NO}_2]^2 \]
This indicates that the rate of the reaction depends only on the concentration of \(\text{NO}_2\) raised to the power of 2.

3. **Determine the Rate-Determining Step**: The rate-determining step (RDS) is the slowest step in the reaction mechanism that controls the overall reaction rate. The rate expression typically reflects the reactants involved in this step.

4. **Analyze the Rate Expression**: Since the rate expression does not include the concentration of \(\text{CO}\), this implies that \(\text{CO}\) is not involved in the rate-determining step.

5. **Conclusion**: Since \(\text{CO}\) does not appear in the rate expression, it means that in the slowest step of the reaction mechanism, there are no molecules of \(\text{CO}\) involved.

Thus, the number of molecules of \(\text{CO}\) involved in the slowest step is:
\[ \text{Number of CO molecules} = 0 \]