Most matter in the natural world is a mixture of substances. Consider seawater, dirt, and plants. Explain why each of these examples of matter is a mixture.

If the chemical properties of a substance remain unchanged and appearance or shape of a substance changes it is called a ?

Two students, each riding bicycles, start from the same apartment building and ride to the same building on campus, but each takes a different route. the first student rides 1100 m due east and then turns due north and travels another 1430 m before arriving at the destination. the second student heads due north for 1930 m and then turns and heads directly toward the destination.at the turning point, how far is the second student from the destination?

In a classical model of the hydrogen atom, the electron moves around the proton in a circular orbit of radius 0.053 nm. what is the electron's orbital frequency? what is the effective current of the electron?