Astack of books are sitting on the table. which force is pulling it down ? a. buoyant force b. pressure force c. gravitational force

There is a gravitational force pulling the stack of books downward. Gravity is always a factor on earth. Keep that in mind when asked these sort of questions. They are made to confuse you. Take your time and you will do just fine.

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.