i think it is 8. I might be wrong.
Water is the only common substance that when you freeze it, it's volume INCREASES.
When the pipe originally held the "all full" volume and the the water expanded, it put a tremendous amount of pressure on the pipe. Enough pressure and the pipe would burst.
The reactivity of a metal is determined by how tightly the metal holds onto the electrons in the outermost energy levels (valence electrons)
Endocytosis
Process by which the cell surrounds and takes particles into the cell
Exocytosis
Secretion of material out of the plasma membrane
