Gas Laws

The concentration of gases like carbon monoxide (CO) is typically expressed in parts per million by volume (ppmv). The concentration in ppmv is generally independent of the temperature, provided the sample is measured in the same way.
However, if the temperature changes, the volume of the gas can change according to the ideal gas law. This change in volume would lead to a change in the concentration if measured by volume. Since the question asks for the concentration at a different temperature (from 25°C to 35°C), we need to understand that the concentration by volume, given the same number of CO molecules, remains constant.
Thus, the correct answer is that the concentration of CO remains the same at 30 ppmv despite the temperature change.
Final Answer:

In proximate analysis, the mass loss in the presence of air is typically used to calculate the percentage of fixed carbon. The mass loss in the absence of air corresponds to the volatile matter, and the difference in mass loss when air is present corresponds to the fixed carbon. Step 1: Find the difference in mass loss.
The mass loss due to the presence of air is . Step 2: Calculate the percentage of fixed carbon.
The percentage of fixed carbon is the ratio of the mass lost in the presence of air to the total mass of the sample: Thus, the fixed carbon percentage is . Final Answer:

We can use the ideal gas law to convert ppm to : where is the molecular weight of NO , given as 46 g/mol. Substituting the values: Thus, the concentration of NO in is .