How are extrusive rocks formed?

they form when magma makes its way to Earth's surface.Then the molten rock erupts or flows above the surface as lava, and then cools forming rock.

Explanation:

this is how they are formed

pla·gia·rism

/ˈplājəˌrizəm/

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noun

the practice of taking someone else's work or ideas and passing them off as one's own.

explanation:

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.