To form a complete monolayer of acetic acid on \( 1 \, \mathrm{g} \) of charcoal, \( 100 \, \mathrm{mL} \) of \( 0.5 \, \mathrm{M} \) acetic acid was used. Some of the acetic acid remained unadsorbed. To neutralize the unadsorbed acetic acid, \( 40 \, \mathrm{mL} \) of \( 1 \, \mathrm{M} \) \( \mathrm{NaOH} \) solution was required. If each molecule of acetic acid occupies \( P \times 10^{-23} \, \mathrm{m^2} \) surface area on charcoal, the value of \( P \) is _______.
[Use given data: Surface area of charcoal \( = 1.5 \times 10^{2} \, \mathrm{m^2 \, g^{-1}} \); Avogadro’s number \( (N_A) = 6.0 \times 10^{23} \, \mathrm{mol^{-1}} \)]
