P = m/v
P = 0.297g/150.0ml
P = 1.98x10^-3 g/ml
Answer. Metals are excellent conductors because the atoms in a metal form a matrix through which their outer electrons can move freely. Instead of orbiting their respective metal atoms, they form a "sea" of electrons that surrounds the positively charged atomic nuclei of the interacting metal ions
I believe there are 3 significant figures B.
