Question

How are extrusive and intrusive rocks formed ? Explain.​

Answer 1

Extrusive rocks are formed on the surface of the Earth from lava, which is magma that has emerged from underground. Intrusive rocks are formed from magma that cools and solidifies within the crust of the planet. ... If lava cools almost instantly, the rocks that form are glassy with no individual crystals, like obsidian.

Step-by-step explanation:

Answer 2

Extrusive rocks are formed on the surface of the Earth from lava, which is magma that has emerged from underground. Intrusive rocks are formed from magma that cools and solidifies within the crust of the planet. ... If lava cools almost instantly, the rocks that form are glassy with no individual crystals, like obsidian.