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![[Post New]](/templates/default/images/icon_minipost_new.gif) 1 Apr 2007 09:49:41 IST
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A teacher enters in class from front door,student enters from back door.There are 12 equidistant row of benches in class. Teacher releases N2O from first bench student releases weeping gas from last bench.At which row,student starts weeping and laughing simultaneously???
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1 Apr 2007 11:51:31 IST
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Its based on Graham's Law of Diffusion...
Wait a moment till i find the solution...
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"If you win, you shall not have to explain and if you lose, you wont be there to explain"
~ Adolph Hitler |
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1 Apr 2007 11:53:49 IST
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Its 9th bench...
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"If you win, you shall not have to explain and if you lose, you wont be there to explain"
~ Adolph Hitler |
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1 Apr 2007 11:54:54 IST
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How did u get it???
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1 Apr 2007 12:08:36 IST
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Use Graham's Law
rate of diffusion fo a gas is inversely proportional to its molecular weight.
Take ratio of rates
But the time for the diffusion will be same for both.
So u are left with ratio of volumes
Volume is length * cross section area
Cross section area same. So cancelled in numerator and denominator
Take length in units of bench
solve the eq. get the ans.
Sorry i could not post the entire solution. Coz its a bit long and difficult to type as it has many subscripts etc...
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"If you win, you shall not have to explain and if you lose, you wont be there to explain"
~ Adolph Hitler |
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1 Apr 2007 12:10:10 IST
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By the way, it should be specified in the ques that weeping gas is C6H11OBr
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~ Adolph Hitler |
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1 Apr 2007 22:45:52 IST
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hiiiii since mol wt. of N2O gas = 44g/mol and mol wt. of tear gas(C6H11OBr)=176g/mol R=rate of diffusion of N2O r=rate of diffusion of tear gas M=mol wt of N2O m=mol wt of tear gas Acc to the formula R/r=sqrt(m/M) R/r=sqrt(176/44) R/r=2 R=2*r This means rate of diffusion of N2O gas is twice the rate of diffusion of tear gas Thts why 9th row will have the tendency of recieving both the gases... Its very easy n short method.hope u like it......
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1 Apr 2007 23:55:57 IST
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It is also very easy to find out the row U jst draw 13 rows on a paper then for every two rows frm the frnt cross one row frm the end n then u will see tht they will meet at the 9th row.  ...thnks |
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4 Apr 2007 09:49:23 IST
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people have done really nice job above
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a 2nd year IIT DELHI student, doing B.Tech in chemical engineering |
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