Which of the following is not considered to be a pollutant ?

Options

A. `NO_(2)`
B. `CO_(2)`
C. `O_(3)`
D. `C_(x)H_(y)`

Answer

To determine which of the following compounds is not considered to be a pollutant, we need to analyze each option provided: NO2, CO2, O3, and hydrocarbons (CX).

### Step 1: Understand what a pollutant is
Pollutants are substances that, when released into the environment, can cause harm to living organisms or the ecosystem. Common pollutants include gases and compounds that result from human activities, especially the burning of fossil fuels.

### Step 2: Analyze each option
1. **NO2 (Nitrogen Dioxide)**: This is a well-known air pollutant that results from combustion processes, such as those in vehicles and power plants. It contributes to smog and respiratory problems.

2. **CO2 (Carbon Dioxide)**: This gas is produced naturally through respiration and is also a byproduct of burning fossil fuels. While it is a greenhouse gas and contributes to global warming, it is not typically classified as a pollutant in the same way as NO2 or O3, especially since it is essential for plant photosynthesis.

3. **O3 (Ozone)**: Ground-level ozone is a significant air pollutant formed by the reaction of sunlight with pollutants like NO2 and volatile organic compounds. It can cause respiratory issues and is a component of smog.

4. **CX (Hydrocarbons)**: These are organic compounds that can be released during the incomplete combustion of fossil fuels. They are considered pollutants as they contribute to smog formation and have various health impacts.

### Step 3: Conclusion
Among the options, CO2 is the one that is not generally considered a pollutant in the same context as the others. While it can contribute to environmental issues like climate change, it does not have the same immediate harmful effects as NO2, O3, or hydrocarbons.

### Final Answer
The compound that is not considered to be a pollutant is **CO2 (Carbon Dioxide)**.

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