Please help me this is for my chem final exam I need help !

What is the ph of a solution that has a hydrogen ion concentration of 1.0 * 10 -9 m?

Draw the lewis dot structure for each of the following polyatomic ions

The famous scientist galileo galilei did several experiments with sloping planes, which he rolled metal balls down so that he could study motion. by changing the slope, he could study how the speed at which the ball rolled was affected. what was the independent variable in galileo's experiment? a. the speed of the ball b. the slope of the plane c. whether the ball moved d. what the ball was made of