Which of the following lists igneous rock in order from least to most ferromagnesian silicates?
intermediate, ultramafic, mafic, felsic
ultramafic, mafic, intermediate, felsic
felsic, intermediate, mafic, ultramafic
felsic, mafic, ultramafic, intermediate

Felsic, intermediate, mafic, ultramafic

Explanation:

Ferromagnesian igneous rocks are those that contains ferromagnesian silicate minerals with magnesium and iron in their structure. Some of these minerals are olivine, pyroxene, amphibole, calcic palgioclase e.tc. Ultramafic rocks have these silicate minerals in them. They impart a dark coloration on their outlook.

Felsic minerals on the other extreme are rich in non-ferromagesian minerals such as quartz, feldspars which lacks magnesium and iron in their structures. The intermediate and the mafic igneous rocks are a mix between the two extremes. So in terms of ferromagnesian silicates component:

    felsic < intermediate < mafic < ultramafic