a saturated solution of milk of magnesia, Mg(OH)2, has a pH of 10.5. What is the hydronium concentration of the solution? is the solution acidic or basic?

Answer 1

The definition of pH is:
pH=-log[H3O+]
An equivalent statement is:
[H3O+] = 10^-pH
The hydronium concentration is the antilog of the (-pH)
For this example,
[H3O+] = 10^-10.5 = ??
The definition acid, basic, and neutral pH's should be something you can look up in your textbook or other assigned materials.