Which of these statements describes a chemical property? A. Iron rusts when exposed to air.
B. Iron melts at 1538°C.
C. Iron is a solid at room temperature.
D. Iron is attracted to a magnet.

Explain the comparisons between nature and packingtown that appears on pages 81 and 82 answer

Two identical stars with mass m orbit around their center of mass. each orbit is circular and has radius r, so that the two stars are always on opposite sides of the circle. (a) find the gravitational force of one star on the other. (b) find the orbital speed of each star and the period of the orbit. (c) how much energy would be required to separate the two stars to infinity?

Adolphin emits ultrasound at 100khz and uses the timing of reflections to determine the position of objects in the water. part a what is the wavelength of this ultrasound? assume that temperature of water is 20 degrees c. answer in cm