Volume of air expands when it is heated. The reason is that atoms of gases in air are always in motion and when they are heated then the kinetic energy of the atoms is increased. As a result of energy increase, the velocity of the atoms increases which makes the gas to expand. Therefore, when air is heated then it expands.
Secondly, metals are good conductors of heat and electricity because of the lone pair of electrons which is available in their outermost shells. When a metal atom is exposed to any sort of energy then these lone pairs of electrons get energy and jump from one shell to the other shell. The continuous movement of electrons from one atom to the other or the flow of electrons result in energy conduction.
Secondly, metals are good conductors of heat and electricity because of the lone pair of electrons which is available in their outermost shells. When a metal atom is exposed to any sort of energy then these lone pairs of electrons get energy and jump from one shell to the other shell. The continuous movement of electrons from one atom to the other or the flow of electrons result in energy conduction.