What should be done to the hydrogen ion concentration to

Question

A fish tank containing a number of exotic fish needs a pH of 5.0 , an indicator indicates the pH of the tank is 7.0. What should be done to the hydrogen ion concentration to set the tank to the correct pH.

At 25^oC, a sample of milk of magnesia, used as an antacid, has a pH of 10.50. What is the [OH^-] in this solution?

A sample of blood at 25^oC has a pH of 7.34. What is the [H3O⁺] in this solution?

An aqueous solution at 25^oC has [OH^-] = 1.0 x 10^-5 M. What is the pH of this solution?

An aqueous solution at 25^oC has [OH^-] = 5.0 x 10^-10 M. What is the pH of this solution?

Which of the following solutions is basic?

i. [H3O⁺] = 2 x 10^-8 M

ii. [OH^-] = 2 x 10^-6 M

iii. [H3O⁺] = 9 x 10^-6 M

Trying to study for my final but kept getting stuck with these questions within a review packet.