Are volcanoes scattered all over the world or do they seem to occur near each other (in groups)?

They are scattered around the world

Volcanoes are not randomly scattered around the world but as in the Pacific Ring of Fire they are usually located where subduction of the oceanic plates beneath continental plates is occurring and for example on the west coasts of North, Central and South America they occur in a linear belt close to the Pacific. 

Answer after wwii, communist countries in eastern europe formed the warsaw pack, a military alliance, and comecon, an economic alliance;