Is rate of diffusion 20micron/sec??
Here your answer is...
Rate of diffusion of gas in720ml/min, i.e.
The volume of gas diffused in 60 seconds (1 min)=720mL
Volume of gas diffused in 20 seconds=6072020=240mL
Hence,240mLof gas diffused in 20 seconds.
Hope this helps you!
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