■A physical property can be observed and the identity of the substance. ●Ex. How something , , , or

e

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.

answer by yourhope:

how do models compare to real-world objects?

d. most models represent a real-world object in a simpler way.

: )