What is a closed system in chemical equilibrium

If the atomic mass of an atom is 34 and the atom contains 13 protons, how many neutrons does the atom contain?

In a copper wire, a temperature increase is the result of which of the following

An animal cell loses the ability to convert energy stored in food to energy that the cell can use. which of the cell's organelles has stopped working? a.the mitochondria b.the nucleus c.the vacuoles d.the endoplasmic reticulum