c
\( {\text{x}} = \sqrt {\frac{{{{\text{K}}_{\text{w}}}}}{{{{\text{K}}_{\text{a}}} \times {K_b}}}} \,\,\, \Rightarrow \,\,\,\,x = \sqrt {\frac{{{{10}^{ - 14}}}}{{1.8 \times {{10}^{ - 5}} \times 1.8 \times {{10}^{ - 5}}}}} \,\,\,\,\therefore \,\,x = 0.55 \times {10^{ - 2}}\)