Stars release vast amounts of energy from their cores, maintaining extremely high temperatures over billions of years. State the name of this nuclear process.

A builder stores water for mixing concrete in an open, wide metal trough. The trough is painted matte black, but on a hot, sunny day, the water evaporates rapidly and the water level falls.

Suggest how, by using a trough of a different shape with the same total volume, the builder can reduce the rate of water loss by evaporation.

The builder is advised to paint the exterior of the trough with shiny silver paint to reduce the amount of radiation absorbed and thus lower the evaporation rate. Describe an experiment to show that matte black surfaces are better absorbers of thermal radiation than shiny silver surfaces.