10- The coefficient of volumetric expansion for gold is 4.20 x 10°/C°. The density of gold is 19 300 kg/m at 0.0 °C. What is the density of gold at 1050 °C?
(a) 20 200 kg/m
(b) 19 000 kg/m
(c) 18 500 kg/m
(d) 19 300 kg/m
(e) 18 800 kg/m

 ρ = 19215 kg / m³ , the answer the correct  is D

Explanation:

All materials are sold when heated, in first approximation

              ΔV = β V₀ (T -T₀)

for this case

              ΔV = 4.20 10⁻⁶ Vo (1050 - 0)

              ΔV = 4.41 10⁻³ Vo m³

              V-Vo = 4.41 10⁻³ Vo

              V = 1.00441 Vo

density is defined by

           ρ = m / V

a T = 0ºc

            ρ₀ = m / Vo

aT= 1050ºC

           ρ = m / V

           ρ = m / (1,00441 Vo)

           ρ = 1 / 1.00441      m/Vo

          ρ = 0.9956 ρ₀

          ρ = 0.9956 19300

          ρ = 19215 kg / m³

when checking the answers the correct one is D

increase masses, decrease separation