Answer:
1. Balance of power refers to a theory in International Relations which suggests that states may secure their survival by preventing any one state from gaining enough military power to dominate all others.
2. The theory suggests that in the event that one state gained too much military power, it would begin to take advantage of its weaker neighbors. To prevent this, states needed to form defensive coalition between each other to prevent one state from becoming too powerful and oppose states trying to become hegemonies, which would allow for peace.
3. The Concert of Europe was the general consensus of the Great Powers of 19th Century Europe to maintain the European balance of power and the integrity of territorial boundaries.
4. Representatives wanted to create a balance of power to preserve peace in Europe, and to prevent one single state to become too powerful, such as the case of the First French Empire lead by Napoleon.
5. For a while, yes. The balance of power prevented one European state from becoming too powerful, eventually however, the rivalries of the great powers and the fragile web of alliances they created would become the catalyst that started several wars, including the Crimean War, Austro-Prussian War, Franco-Prussian War, Russo-Turkish War and The First World War.