Weegy: Ozone forms when hydrocarbons and nitrogen oxides combine in the presence of sunlight. Ozone is a secondary pollutant. User: Which processes are responsible for uneven distribution of metals in Earth’s crust? How do these processes cause metals to be distributed? Weegy: The processes that are responsible for uneven distribution of metals in Earth's crust is: Earth formed from cosmic dust in the solar system. [ As it cooled, heavier elements, such as iron, sank toward the core, while lighter elements, such as silica, floated toward the surface. ] User: What is the biggest problem with desalination? (More)