Calculate 2x10-3 cm divided by 2.5 x 10/4 cm

Explain earth's motion, using the terms "precession" and "rotation" in your answer.

If an atom contains 11 protons in its nucleus, predict the element with the atomic number and electronic configuration. will the number of electrons remain the same during the chemical reaction in such an atom? explain.

The air that we breath is made mostly of which gaseous molecule