QJEEM19Chf098: JEE Main 2019 Chemistry - Class 12 JEEM19Chf098 Solution: 10 mL of 1mM surfactant solution forms a monolayer covering…

No of moles formed = 10^-3 $\times$ ${{10} \over {1000}}$ = 10^-5

$\therefore$ No of molecules formed = 10^-5 $\times$ N_A

In unimolecular layer formation each cube occupy an area = a²

$\therefore$ Total area occupied = 10^-5 $\times$ N_A $\times$ a²

According to the question,

10^-5 $\times$ N_A $\times$ a² = 0.24

$\Rightarrow$ 10^-5 $\times$ 6 $\times$ 10²³ $\times$ a² = 0.24

$\Rightarrow$ a² = 4 $\times$ 10^-20

$\Rightarrow$ a = 2 $\times$ 10^-10 cm = 2 pm