What is the purpose of a salt bridge in an electrochemical cell?

Can someone me with 6 to 10 plz this is for masteries test.

The msds for glacial acetic acid says that it is a flammable liquid that can severely burn any human tissue it comes in contact with. it reacts with bases, various metals, and strong oxidizing agents. its vapors can form explosive mixtures with air.

How many moles are contained in 5.6 l of h2 at stp