Which of the following mixtures of gases does not obey Dalton’s law of partial pressure?

Options

A. `O_(2)` and `CO_(2)`
B. `N_(2)` and `O_(2)`
C. `Cl_(2)` and `O_(2)`
D. `NH_(3)` and HCl

Answer

To determine which of the following mixtures of gases does not obey Dalton’s law of partial pressure, we first need to understand the law itself. Dalton's Law states that in a mixture of non-reacting gases, the total pressure exerted by the mixture is equal to the sum of the partial pressures of each individual gas. This law holds true only for gases that do not react with each other.

### Step-by-Step Solution:

1. **Understand Dalton's Law of Partial Pressure**:
- Dalton's Law states that the total pressure of a gas mixture is equal to the sum of the partial pressures of its individual components.
- Mathematically, it can be expressed as:
\[ P_{total} = P_1 + P_2 + P_3 + \ldots + P_n \]
- Where \( P_1, P_2, \ldots, P_n \) are the partial pressures of the individual gases.

2. **Identify the Gases in the Mixtures**:
- We need to analyze the given mixtures of gases to check if they are reacting or non-reacting.
- For example, consider the following mixtures:
- O2 and CO2
- N2 (Nitrogen)
- Cl2 (Chlorine) and O2
- NH3 (Ammonia) and HCl (Hydrochloric acid)

3. **Analyze Each Mixture**:
- **O2 and CO2**: These gases do not react with each other. Therefore, they obey Dalton's Law.
- **N2**: Nitrogen is chemically inert and does not react with itself or other gases. It obeys Dalton's Law.
- **Cl2 and O2**: Chlorine and oxygen do not react under normal conditions, so they obey Dalton's Law.
- **NH3 and HCl**: Ammonia and hydrochloric acid react to form ammonium chloride (NH4Cl). This is a chemical reaction, and thus, they do not obey Dalton's Law.

4. **Conclusion**:
- The mixture that does not obey Dalton's Law of Partial Pressure is **NH3 and HCl** because they react with each other.

### Final Answer:
The mixture of gases that does not obey Dalton’s Law of Partial Pressure is **NH3 and HCl**.