The classroom consists of 30 equidistant rows of benches. A student from first benches release (N2O) nitrous oxide (laughing gas) where a student of last bench releases tear gas (C10H5ClN2=2-chlorobenzalmalononitrile) simultaneously. Find out the which benches students starts laughing and weeping simultaneously.

The Molecular weight (M_A) of N₂O (laughing gas = 44 gm/mol.

Molecular weight (M_B) of (C₁₀H₅ClN₂) (Tear gas) = 179 gm/mol.

(r₁/r₂) = √{ (M_B/M_A) }

(r₁/r₂) =√{ (179/44) }

(r₁/r₂) = √4

(r₁/r₂) = 2

Now let s take “x” as the row from where student start laughing and weeping simultaneously.

Therefore:

(X/30- x) = 2

x = 2(30- x)

 x = 60-2x

3x = 60

  x = 20

Therefore, from 20^th row where students will start weeping and laughing simultaneously.

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