Explain how density is involved in convection.

Cold air is dense and warmer air is less dense and so as the cool dense air sinks the warm air rises and takes its place causing a convection current. This is the same with water and other gaseous and liquid substances.

Probably north korea if your family has decided to use only nuclear power.

Aregion is an area of land that has common features. these features can be natural, such as climate or landscape. they can also be artificial, such as language or religion. the xinjiang uyghur autonomous region, above, is an area of china inhabited by uyghurs, a muslim group with ethnic ties to turkish people.