Volcanoes

Which types of magma contains the least amount of SiO₂

• rhyolitic
• andesitic
• felsic
• basaltic

Rhyolitic magma is rich in _____.

• silica
• iron
• magnesium
• sulfur

Which of the following is not a factor that can affect magma composition

• lacosity
• mineral content
• silica
• water content

The composition of magma determines its _____.

• viscosity
• darkness
• color
• none of the above

Which of the following gases is not typically found in volcanic activity?

• water vapor
• sulfur
• carbon dioxide
• argon

Volcanoes that are made of basalt lava flows are called _____.

• shield volcanoes
• composite volcanoes
• stratovolcanoes
• cone volcanoes

Volcanoes are common along

• convergent plate boundaries.
• divergent plate boundaries.
• transform plate boundaries.
• two of the above

About 75 percent of the world’s volcanoes are found 

• around the Atlantic Ocean basin.
  
• along the mid-Atlantic ridge.
  
• around the Pacific Ocean basin.
  
• throughout the American Northwest. 

A  line of volcanic activity that surrounds the Pacific Ocean basin is the 

• Ring of Fire
• Aleutian Islands
• Hawaiian Islands
• Caribbean Islands

Which of these volcanic particulates is the largest in size?

• Block
• Ash
• Bomb
• Lapilli