5. Why is the perimeter around the Pacific Ocean referred to as the “ring of fire”?

Because it marks the rims of tectonic plates and is very active, geologically, in most places. Lots of volcanoes and earthquakes.

The pacific ocean lies on the pacific plate and as it interacts with the surrounding continental plates it causes volcanic eruptions to occur therefore spawning the name ring of fire

The perimeter around the Pacific Ocean is referred to as the "Ring of Fire because it is a zone of frequent earthquakes and volcanic eruptions that encircles the basin of the Pacific Ocean. 90% of the world's earthquakes and 81% of the world's largest earthquakes occur along the Ring of Fire.

The ring of fire is a circle of volcanos, and they cricle them. soooo. yup.

because it is a ring of plate tectonics and volcanoes

Because of the great number of active volcanoes along the perimeter!