The pH of a 0.00100 M solution of a particular acid is 4.95 at 25°C.
Use the solution pH to calculate the concentration of hydronium ion present [H3O+]
pH = -log(H3O^+)
4.95 = -log(H3O^+)
-4.95 = log(H3O^+)
Another way of writing this is
(H3O^+) = 10^-4.95
Solve for (H3O^+)