Answer: The correct answer is Option A.
Step-by-step explanation:
pH is defined as negative logarithm of hydronium ion concentration. It is basically defined as the power of hydrogen ions that are present in a solution.
Mathematically,
![pH=-\log[H_3O^+]](https://img.qammunity.org/2020/formulas/chemistry/high-school/f390cegazdnm7uy3e4lyqajx4gquacwg62.png)
pH of the solution = 9.11
Putting values in above equation, we get:
![9.11=-\log[H_3O^+]](https://img.qammunity.org/2020/formulas/chemistry/college/ujrn4ztg0rq55vu97fqp0g5db7xzcurq1w.png)
![[H_3O^+]=antilog(-9.11)](https://img.qammunity.org/2020/formulas/chemistry/college/g77326f2d3ju8n58k4vvsyun0msm2vuzm2.png)
![[H_3O^+]=7.8* 10^(-10)](https://img.qammunity.org/2020/formulas/chemistry/college/cvxq0uu4fj32zpb7bej1nkhtvz0cb3l4sg.png)
Hence, the correct answer is Option A.