How many atoms are in a single grain of sand?

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.

Drag each tile to the correct box. tiles bra i sequence

In which type of system is power held solely by the central government and not shared with regional governments? group of answer choices federal unitary confederate oligarchic