How do you do this problem ?

Question

Which set of characteristics best describes mafic magma?
high silica content, thin and fluid, forms dark-colored rock
high silica content, thick and slow-flowing, forms light-colored rock
low silica content, thin and fluid, forms dark-colored rock
low silica content, thick and slow-flowing, forms light-colored rock

Answer 1

mafic magma is one that contains magnesium and iron, so will be dark colored, and will be low in silica content.

Answer 2

http://www.physicalgeography.net/physgeoglos/m.html#mafic_magma this will answer your question and possibly many others it is top to bottom on these types of rocks and easy to follow.