Magma consists of oxides of silicon, aluminum, magnesium, iron, calcium, sodium and potassium. Why is this so?
A) They are all heavy elements located beneath the surface of the earth.
B) They are all attracted to heat.
C) They all have low melting points.
D) They are all oxides.
Question 2
Igneous rocks are overwhelmingly composed of silicate minerals. Why is this so?
A) Silicates are very heavy.
B) Silicates compose a huge amount of the earth's crust.
C) Silicates are only found in igneous rocks.
D) Silicates are very rare.
