-- The crust is very
compared to
the other layers. It is
composed of solid
that is broken
into

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.

um i think it might be a car?

here are some of the ways in which chemical and nuclear reactions differ.

explanation: