What is the ph of a solution with a hydrogen ion concentration of 2.4 x 10-5?

Iknow the answer to 13 is b and 14 is d. i just need to know why the correct answers are correct

There is an area in idaho named craters of the moon where most of the ground is covered with basalt, adark gray, igneous rock with no visibl crystals. what can you infer about the geographical history of the area?

Asolid that forms and separates from a liquid mixture is called