When a metal is heated, its density decreases. there are two sources that give rise to this decrease of p: (1) the thermalexpansion of the solid and [2) the formation of vacancies (section 4.2). consider a specimen of gold at room temperature(20°c) that has a density of 19.320 g/cm3.(a) determine its density upon heating to 800°c when only thermal expansion is considered.(b) repeat the calculation when the introduction of vacancies is taken into account assume that the energy of vacancyformation is 0.98 ev/atom, and that the volume coefficient of thermal expansion. av is equal to 30/.