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Basics of Organic Chemistry question

2022 · 25 Jul · Shift 2 · Q21
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Basics of Organic Chemistry question

2022 · 25 Jul · Shift 2 · Q21

JEE MainChemistryBasics of Organic ChemistryNumerical+4 / −1
The separation of two coloured substances was done by paper chromatography. The distances travelled by solvent front, substance A and substance B from the base line are 3.25 cm, 2.08 cm and 1.05 cm, respectively. The ratio of Rf values of A to B is ‾\underline{\hspace{2cm}}​.
Numerical answer
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Correct answer: 2

  1. In paper chromatography, the retardation factor RfR_fRf​ is defined as:

Rf=distance travelled by substancedistance travelled by solvent frontR_f = \frac{\text{distance travelled by substance}}{\text{distance travelled by solvent front}}Rf​=distance travelled by solvent frontdistance travelled by substance​

  1. For substance A:

Rf(A)=2.083.25R_f(A) = \frac{2.08}{3.25}Rf​(A)=3.252.08​

  1. For substance B:

Rf(B)=1.053.25R_f(B) = \frac{1.05}{3.25}Rf​(B)=3.251.05​

  1. Therefore, the ratio of RfR_fRf​ values is:

Rf(A)Rf(B)=2.083.251.053.25=2.081.05\frac{R_f(A)}{R_f(B)} = \frac{\frac{2.08}{3.25}}{\frac{1.05}{3.25}} = \frac{2.08}{1.05}Rf​(B)Rf​(A)​=3.251.05​3.252.08​​=1.052.08​

  1. Now calculate:

2.081.05≈1.98≈2\frac{2.08}{1.05} \approx 1.98 \approx 21.052.08​≈1.98≈2

  1. Hence, the required integer answer is:

2\boxed{2}2​

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