\(a,\left[OH^-\right]=0,0002.2=0,0004\left(M\right)\\ \Rightarrow pH=14+log\left[OH^-\right]=14+log\left[0,0004\right]\approx10,602\)
\(b,\left[H^+\right]=\left[HCl\right]=0,1\left(M\right)\\ \Rightarrow pH=-log\left[H^+\right]=-log\left[0,1\right]=1\)
\(a.\left[OH^{^{ }-}\right]=2.0,0002=0,0004\left(M\right)\\ b.\left[H^{^{ }+}\right]=0,1\\ pH=-log\left[H^{^{ }+}\right]=1\)