JEE Main 2019 — Solid State Question with Solution
From: JEE Main 2019 (Online) 9th April Evening Slot
Question
10 mL of 1mM surfactant solution forms a
monolayer covering 0.24 cm2 on a polar
substrate. If the polar head is approximated as
cube, what is its edge length?
Choose an option
Show full solutionCorrect option: D
Correct answer
D2.0 pm
Step-by-step explanation
No of moles formed = 10-3 = 10-5
No of molecules formed = 10-5 NA
In unimolecular layer formation each cube occupy an area = a2
Total area occupied = 10-5 NA a2
According to the question,
10-5 NA a2 = 0.24
10-5 6 1023 a2 = 0.24
a2 = 4 10-20
a = 2 10-10 cm = 2 pm
No of molecules formed = 10-5 NA
In unimolecular layer formation each cube occupy an area = a2
Total area occupied = 10-5 NA a2
According to the question,
10-5 NA a2 = 0.24
10-5 6 1023 a2 = 0.24
a2 = 4 10-20
a = 2 10-10 cm = 2 pm
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This is a previous-year question from JEE Main 2019, covering the Solid State 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.