Section #: 5.1
What Are Igneous Rocks?
Practice Test
1.
What is the source of heat inside Earth that melts rocks into magma?
a.
geothermal energy
b.
other molten rocks
c.
Earth's core is hotter for no reason.
d.
the decay of radioactive elements
Hint
2.
Extrusive rocks have fine-grained textures because __________.
a.
they are derived from volcanoes
b.
they cooled slow
c.
they cooled quickly
d.
they cooled inside Earth's crust
Hint
3.
Granite is an example of __________ rock.
a.
an intrusive igneous
b.
a partially melted
c.
an extrusive igneous
d.
a volcanic ash
Hint
4.
What process explains why a molten magma often is a mix of molten rock and crystals?
a.
plate tectonics
b.
melting points
c.
Bowen's reaction series
d.
partial melting
Hint
5.
What branch of Bowen's reaction series cools with a continuous change in composition?
a.
the feldspars
b.
the silica chains
c.
the iron-magnesium groups
d.
the carbonates
Hint
6.
Peridotite and dunite have __________ compositions.
a.
felsic
b.
intermediate
c.
ultramafic
d.
mafic
Hint
7.
What is the last mineral to form on the left branch of Bowen's reaction series?
a.
quartz
b.
pyroxene
c.
olivine
d.
feldspar
Hint
8.
__________ explains the relationship between cooling magma and mineral formation.
a.
Bowen's reaction series
b.
Branches of crystallization
c.
Geothermal gradients
d.
Partial melting
Hint
9.
What extrusive igneous rock has a mafic composition and a glassy texture?
a.
diorite
b.
obsidian
c.
basaltic glass
d.
gabbro
Hint
10.
Igneous rocks that cool on Earth's surface are called __________.
a.
molten
b.
intrusive
c.
lava
d.
extrusive
Hint
11.
How are igneous rocks formed?
a.
from the compaction of loose sediments
b.
from increased pressures and temperatures
c.
from the crystallization of magma
d.
from the cementation of mineral grains
Hint
12.
According to the figure showing a limited view of Bowen's reaction series, what type of mineral causes a continuous reaction series?
a.
calcium
b.
sodium
c.
iron
d.
magnesium
Hint
13.
Which is not a compositional classification of a magma?
a.
basaltic
b.
rhyolitic
c.
andesitic
d.
phaneritic
Hint
14.
What is the temperature change in Earth's crust called?
a.
radioactive decay
b.
thermal energy
c.
hydrothermal gradient
d.
geothermal gradient
Hint
15.
Which rock has an intermediate composition?
a.
basaltic
b.
rhyolite
c.
diorite
d.
dunite
Hint
16.
Oceanic crust melts at __________ than continental crust.
a.
lower temperatures
b.
the same temperature
c.
higher temperatures
d.
higher pressures and lower temperatures
Hint
17.
According to the figure, what happens to the melting point of rock as the depth and pressure increases?
a.
it increases sharply
b.
it increases gradually
c.
it decreases sharply
d.
it decreases gradually
Hint
