Correct option is (2) 4
Degree of dissociation of HA (α) = \(\frac{∧m}{∧^{\infty} m}\)
= \(\frac{3.907 scm^2mol^{-1}}{390.7 scm^2mol^{-1}}\)
= 10-2
α = 0.01
\(\therefore\) [H+] = Cα
= 0.01 x 0.01 = 10-4M
\(\therefore\) PH = -log[H+] = -log10-4
PH = 4