a, \(\left[H^+\right]=0,1=10^{-1}\Rightarrow pH=1\)
b, \(\left[H^+\right]=2.0,05=10^{-1}\Rightarrow pH=1\)
c, \(\left[OH^-\right]=0,2\)
\(\Rightarrow\left[H^+\right]=5.10^{-14}\)
\(\Rightarrow pH\approx13,3\)
d, \(\left[OH^-\right]=2.0,025=0,05\)
\(\Rightarrow\left[H^+\right]=2.10^{-13}\)
\(\Rightarrow pH\approx12,7\)