Which type of change results in a new substance being produced?

1) chemical 2) mass 3) physical 4) change of state

Which two particles are found in the center of an atom

If y gets smaller as x gets bigger and y have an relationship?

Consider an insulating crystal, made up of layers of atoms. what form would you expect the temperature dependence of the phonon heat capacity to approach at extremely low temperatures if the interlayer coupling is i)very strong (rigid coupling), and ii) very weak. explain.