GATE 2022 CE (CE2) – Question 61
A sample of air analyzed at 25 °C and 1 atm pressure is reported to contain 0.04 ppm of SO2. Atomic mass of S = 32, O = 16. The equivalent SO2 concentration (in μg/m3) will be__________. (round off to the nearest integer)
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Correct answer: 105
Explanation
At 25°C and 1 atm the ideal-gas molar volume is approximately 24.45 L/mol. Conversion is $\mathrm{mg/m^3}=ppm\times MW/24.45$.
For SO₂, MW=64, giving $0.04(64)/24.45=0.104703$ mg/m³=104.703 μg/m³. **Answer: 105 μg/m³**.