JEE Main 2017ChemistrySolutionsMediumMCQ

JEE Main 2017 — Solutions Question with Solution

JEE Main 2017 (08 Apr Online)

Question

5g of Na2SO4 was dissolved in x g of H2O . The change in freezing point was found to be 3.82oC . If Na2SO4 is 81.5% ionised, the value of x

( Kf for water =1.86oC kg mol-1 ) is approximately:

(molar mass of S=32 g mol-1 and that of Na=23 g mol-1 )

Choose an option

Show full solutionCorrect option: D
Correct answer
D45 g

Step-by-step explanation

Na2SO4→2Na++SO42-

i=1+3-1 0.815=2.63

3.82=1.86×2.63×5×1000142×x

∴ x=1.86×2.63×5000142×3.82

=45 gm

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About this question

This is a previous-year question from JEE Main 2017, covering the Solutions chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.