Q31 / 48 · NTA Abhyas (JEE Main) 2020 · Chemistry · Surface Chemistry

10 mL of 1 mM 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?

  • Correct answer
    A
    2.0 pm
  • B
    2.0 nm
  • C
    1.0 pm
  • D
    0.1 nm

Solution

Millimoles =10×10-3=10-2

Moles =10-5

No. of molecules =6×1023×10-5=6×1018

Surface area ocupied by one molecule

=0.246×1018=0.04×10-18cm2

4×10-20=x2[∵x= edge length ]

x=2×10-10 cm =2 pm

Hence, the correct answer is option: 'A'.

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