Use the information about igneous rocks A-D to classify each one as intrusive or extrusive and basaltic or granitic. Fill in the chart with A, B, C, or D.
Rock A-dark-colored large grains
Rock B-large crystals, high percentage of silica
Rock C-fine-grained texture, light-colored
Rock D-from Hawaiian volcano area, no visible crystal

Extrusive or volcanic rocks crystallize from lava at the earth's surface. The texture of an igneous rock (fine-grained vs coarse-grained) is dependent on the rate of cooling of the melt: slow cooling allows large crystals to form, fast cooling yields small crystals.

Out of the following given choices;

A rapid cooling of the molten rock

B high density of the molten rock

C numerous faults in the island’s bedrock

D high pressure under the island

The answer is; A

When the magma rises from the mantle onto the earth surface in the region, it encounters ice-cold temperatures that cool the magma rapidly. This reduces the time that large mineral crystals (typical of slow-cooling) can form in the cooling rock hence the typical characteristic of these rocks are fine-grained and brittle.