The net ionic equation is an equation showing only the ions that take part in the reactions. The ions that do not take part in the chemical reaction known as spectator ions are not shown when writing net ionic equations.
Spectator ions are those ions that do not change state after the chemical reaction has taken place. In this case, hydrogen ions and carbonate ions are spectator ions.
D. A disadvantage of nuclear power is that waste products are unsafe and hard to store. They must be stored for many hundreds of years before they becomes safe and easier to dispose of, and we currently don't have a good method of storing them in the meantime.