When magma cools rapidly, nucleation (increases/decreases) the rate of crystal growth (increases/decreases) and the resulting rock is .

Explanation:

When magma cools rapidly, nucleation (increases/decreases) ___increases, the rate of crystal growth (increases/decreases) decreases, and the resulting rock is fine-grained.

Nucleation is a process in crystal formation whereby ions begins to combine to form minerals. This is usually the first phase of mineral formation and crystal growth. During nucleation, the regualar ordering of crystals begins to take shape. In magma that cools rapidly, nucleation is very fast and several small nuclei are formed.

Due to the fast paced cooling, the rate of crystal growth is very fast. It takes time for crystals to grow and aggregate into larger ones. When cooling is rapid, this is not the case. The formation of smaller crystals results.

The resulting rock is usually fine grained when nucleation is fast and the rate of crystal growth is also fast.

thats how its supposed to be