Home › Previous year questions › GATE 2021 ES › Question 14GATE 2021 ES – Question 14 Air and Noise Pollution · Atmosphere and Air Quality · 1 mark · Multiple choice
An air sample has 30 ppmv CO at 25°C in the morning. The same sample is analysed at 35°C later. What is its CO concentration in ppmv?
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Show answer and explanation Correct answer: (C) =30
Explanation For an unchanged ideal gas mixture, volume fraction equals mole fraction. Heating changes component and total volumes proportionally, so their ratio remains30×10⁻⁶. Thus **30 ppmv, C**. Mass concentration per cubic metre would change with temperature at fixed pressure, but ppmv does not.
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