What do chemistry study? A. How matter and energy interact B. Mathematical principles C. The properties of matter and how matter changes D. Living things

The allotropes of carbon include a variety of structures that include three-dimensional tetrahedral lattices, planes of hexagonal rings, cylindrical tubes of hexagonal rings, and spheres of five- and six-membered rings. similar shapes of network covalent atomic solids are possible with carbon nitride, boron, and pure silicon (e.g., silicene is a graphene-like allotrope of pure silicon). in contrast, silicates exist as either highly ordered or amorphous (more random) three-dimensional lattices. what could explain why there are there no naturally occurring sheets, stacked sheets, cylindrical tubes, or spheres of network covalent atomic solids composed of silicon and oxygen (sio2)? would pure silicate structures make good lubricants or good electrical conductors?

Suppose you increase your walking speed from 7 m/s to 15 m/s in a period of 1 s. what is your acceleration?

The hammering on a train track is often heard twice by workers farther down the track; first as the sound travels through the steel and second as the sound travels through the air. this suggests which graph is true?