What is the density of a gas (in g/cm^3) if 3.0 gram sample occupies a volume of 1.0 m^3

Which of the following are properties of mechanical waves? check all that apply ⭕️ particles of the medium move back and fourth, but do not move with the wave. ⭕️ the particles of the medium always move parallel to the wave motion. ⭕️ wave motion begins with a disturbance in the medium. ⭕️ waves transport energy from a source outward, away from the source.

Anybody wanna ? (picture included? )

Because light travels in a straight line and casts a shadow, isaac newton hypothesized that light is