Why must weathering, erosion, and deposition take place to form a river delta?

In the first law of thermodynamics, triangle e=q-w, what does q stand for

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.

The ozone hole appears in antarctica during