Igneous rocks with large crystals are because they cool and the surface.

intrusive, quickly, above

extrusive, quickly, below

extrusive, slowly, above

intrusive, slowly, below

Intrusive, slowly, below

Explanation:

There are three types of rocks- Sedimentary,Metamorphic and Igneous. Igneous rocks are formed when the molten(after melting by various processes) start getting crystallised below the surface.

.The molten rock materials consists of the magma and Lava. Melting can be caused by either increase in temperature or any other reason.

Intrusive ones solidify below Earth's surface and they start to cool slowly . Due to this reason we can see large crystals unlike other types of rocks. They are found on the crust of Earth.

Intrusive rocks are most common and constitute most of the igneous rocks.

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.