For each question below, choose the letter corresponding to the BEST answer.

1		Mt. St. Helens: Need a Hint?
			A)	is part of the Cascade Range.
			B)	is located in southern Washington.
			C)	last major eruption was in 1980.
			D)	all of these
2		Volcanic eruptions can affect climate because: Need a Hint?
			A)	volcanoes have no effect on Earth's climate.
			B)	I told you so in class.
			C)	volcanic dust and gas in the upper atmosphere reflects and absorbs solar radiation.
			D)	they heat the atmosphere.
3		Magma extruded at high temperatures tends to be: Need a Hint?
			A)	very explosive.
			B)	very fluid.
			C)	very viscous.
			D)	very unwelcome at a party.
4		Magma with a high silica content tends to be: Need a Hint?
			A)	very smelly.
			B)	very viscous.
			C)	very hot.
			D)	also very unwelcome at a party.
5		Magma with a large amount of dissolved gases tends to be: Need a Hint?
			A)	very messy.
			B)	very viscous.
			C)	very explosive.
			D)	really truly very unwelcome at a party.
6		Magma is: Need a Hint?
			A)	the reason volcanoes form.
			B)	the source of all igneous rocks.
			C)	melted rock.
			D)	all of these
7		Which of the following does not affect the viscosity of magma? Need a Hint?
			A)	amount of gases
			B)	silica content
			C)	temperature
			D)	All of these affect the viscosity of a magma.
8		Which of these is not a common gas in magma? Need a Hint?
			A)	methane
			B)	sulfur dioxide
			C)	carbon dioxide
			D)	water vapor
9		The asthenosphere is: Need a Hint?
			A)	heated by the presence of magma.
			B)	the source of most magmas.
			C)	completely molten.
			D)	all of these
10		Submarine eruptions of volcanoes: Need a Hint?
			A)	have never been observed.
			B)	cannot occur because water causes magma to solidify too quickly.
			C)	form pillow basalts.
			D)	none of these
11		The greatest single volcanic eruption that geologists have documented is: Need a Hint?
			A)	Agung, Indonesia.
			B)	Tambora, Indonesia.
			C)	Krakatau, Indonesia.
			D)	Toba, Indonesia.
12		A typical example of a shield volcano is: Need a Hint?
			A)	Mt. Pinatubo.
			B)	Mt. Ranier.
			C)	Hawaii.
			D)	Mt. St. Helens.
13		Which type of volcano is not commonly composed of basalt? Need a Hint?
			A)	composite volcano
			B)	cinder cone
			C)	spatter cone
			D)	shield volcano
14		An igneous rock made of pyroclasts has a texture called: Need a Hint?
			A)	fine-grained.
			B)	vesicular.
			C)	porphyritic.
			D)	fragmental.
15		The largest known volcano is: Need a Hint?
			A)	Iceland.
			B)	Olympus Mons (Mars).
			C)	Hawaii.
			D)	Mt. Ranier.
16		Crater Lake in Oregon is an example of: Need a Hint?
			A)	a volcanic bomb.
			B)	a cinder cone.
			C)	a caldera.
			D)	a shield volcano.
17		Mafic igneous rocks contain: Need a Hint?
			A)	about 80% silica.
			B)	about 70% silica.
			C)	about 60% silica.
			D)	about 50% silica.
18		Obsidian is an igneous rock that: Need a Hint?
			A)	solidified in Earth's mantle.
			B)	solidified beneath Earth's surface.
			C)	solidified very slowly to form pegmatite.
			D)	solidified very rapidly to form glass.
19		The most common type of volcano in the "Ring of Fire" is: Need a Hint?
			A)	a volcanic fissure.
			B)	a cinder cone.
			C)	a shield volcano.
			D)	a composite volcano
20		Which planet is not known to have volcanoes? Need a Hint?
			A)	Saturn
			B)	Mars
			C)	Earth
			D)	Venus