Verified Solution • 2025–26 Session moderate

QJEEM20Chb67e: JEE Main 2020 Chemistry - Class 12 JEEM20Chb67e Solution: A set of solutions is prepared using 180 g of water as a…

A set of solutions is prepared using 180 g of water as a solvent and 10 g of different nonvolatile solutes A, B and C. The relative lowering of vapour pressure in the presence of these solutes are in the order :

[Given, molar mass of A = 100 g mol–1; B = 200 g mol–1; C = 10,000 g mol–1]

Multiple Choice Options

  • A A > C > B
  • B C > B > A
  • C A > B > C
  • D B > C > A

Step-by-Step Verified Solution

Relative lowering in vapour pressure (RLVP)

= P−PsP=nn+N{{P - {P_s}} \over P} = {n \over {n + N}}

n →\to moles of solute
N →\to moles of solvent

∴\therefore (RLVP)A = 1010010100+18018{{{{10} \over {100}}} \over {{{10} \over {100}} + {{180} \over {18}}}}

(RLVP)B = 1020010200+18018{{{{10} \over {200}}} \over {{{10} \over {200}} + {{180} \over {18}}}}

and (RLVP)C = 10100001010000+18018{{{{10} \over {10000}}} \over {{{10} \over {10000}} + {{180} \over {18}}}}

∴\therefore (RLVP)A > (RLVP)B > (RLVP)C

So, A > B > C

Related Learning Resources & Exam Preparation

JEE Main PYQ Question Bank
Browse year-wise authentic previous years' questions with solutions
Authentic CBT Mock Tests
Simulate official exam environment with live timer and percentile scoring