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 understand why the reaction \(2NO + O_2 \rightarrow 2NO_2\) is faster than \(2CO + O_2 \rightarrow 2CO_2\), we need to analyze the concept of activation energy (EA) and how it affects the rate of reactions.

### Step-by-Step Solution:

1. **Identify the Reactions**:
- The first reaction is \(2NO + O_2 \rightarrow 2NO_2\).
- The second reaction is \(2CO + O_2 \rightarrow 2CO_2\).

2. **Understanding Activation Energy**:
- Activation energy is the minimum energy required for a reaction to occur. It is the energy barrier that reactants must overcome for a reaction to proceed.

3. **Compare Activation Energies**:
- The reaction \(2NO + O_2\) has a lower activation energy compared to the reaction \(2CO + O_2\). This means that it requires less energy for the reactants to collide effectively and form products.

4. **Effect on Reaction Rate**:
- A lower activation energy results in a higher reaction rate because more molecules have sufficient energy to overcome the energy barrier. Therefore, \(2NO + O_2\) reacts faster than \(2CO + O_2\).

5. **Conclusion**:
- The reason the first reaction is faster than the second is that the activation energy for the formation of \(NO_2\) is lower than that for the formation of \(CO_2\). Hence, the correct answer is that the first reaction has lower activation energy than the second.