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AP EAMCET · Chemistry · States of Matter

Among the following, identify the gas which has the greatest average speed of its molecules?

  1. A \(0.5 \mathrm{~mol}\) of \(\mathrm{O}_2\) at \(500 \mathrm{~K}\)
  2. B \(0.2 \mathrm{~mol}^2 \mathrm{CO}_2\) at \(400 \mathrm{~K}\)
  3. C \(1.0 \mathrm{~mol}\) of \(\mathrm{He}\) at \(200 \mathrm{~K}\)
  4. D \(0.4 \mathrm{~mol}\) of \(\mathrm{NH}_3\) at \(300 \mathrm{~K}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(1.0 \mathrm{~mol}\) of \(\mathrm{He}\) at \(200 \mathrm{~K}\)

Step-by-step Solution

Detailed explanation

The average molecular speed is inversely proportional to the square root of molar mass. \(v=\sqrt{\frac{8 R T}{\pi M}}\) i.e. \(v \propto \frac{1}{\sqrt{M}}\) Among \(\mathrm{O}_2, \mathrm{CO}_2\), He and \(\mathrm{NH}_3\), He has very low molar mass. Therefore, it has greatest…