• # question_answer The pH of a ${{10}^{-10}}$molar solution of $HCl$ in water is A)  6.0                B)  7.0                 C)       8                  D)       13

Total concentration of ${{\text{H}}^{\text{+}}}$ions $={{10}^{-10}}+H{{O}^{-7}}$ $(HCl)\,\,\,({{H}_{2}}O)$ $={{10}^{-10}}(1+{{10}^{3}})=1001\times {{10}^{-10}}.$ So, $pH=-\log (1001\times {{10}^{-10}})$ $=10-3$ $=7$ Hence, the correct option is (b).