The reactions `2NO+O_(2) rarr 2NO_(2)`
`2CO+O_(2) rarr 2CO_(2)`
look to be identical, yet the first is faster than the second. The reason is that

Options

A. the first reaction has lower enthalpy change than the second
B. the first reaction has lower internal energy change than the second
C. the first reaction has lower activation energy than the second
D. nitric oxide is less stable than carbon monoxide

Explanation

To solve the question regarding the reactions \(2NO + O_2 \rightarrow 2NO_2\) and \(2CO + O_2 \rightarrow 2CO_2\), we will analyze the factors that affect the rate of these reactions.

### Step-by-Step Solution:

1. **Understanding the Reactions**:
- We have two reactions: one involving nitrogen monoxide (NO) and the other involving carbon monoxide (CO). Both reactions involve the same reactant \(O_2\) and produce different products.

2. **Rate of Reaction**:
- The rate of a chemical reaction is influenced by several factors, including concentration, temperature, and activation energy (EA).

3. **Activation Energy (EA)**:
- Activation energy is the minimum energy required for a reaction to occur. It is a crucial factor in determining the rate of a reaction. Lower activation energy generally leads to a faster reaction.

4. **Comparing Activation Energies**:
- In this case, the question states that the reaction \(2NO + O_2 \rightarrow 2NO_2\) is faster than \(2CO + O_2 \rightarrow 2CO_2\). This suggests that the activation energy for the first reaction (NO) is lower than that for the second reaction (CO).

5. **Conclusion**:
- Since the activation energy for the reaction involving NO is lower, it requires less energy for the reaction to proceed, resulting in a faster reaction rate compared to the reaction involving CO.

6. **Final Answer**:
- The reason the first reaction is faster than the second is that the activation energy for the reaction \(2NO + O_2 \rightarrow 2NO_2\) is lower than that for \(2CO + O_2 \rightarrow 2CO_2\).