Which of the following statements about the sun is true? a. the sun is made up mostly of helium and carbon dioxide. b. the outer layer of the sun is also its most dense layer. c. the sun rotates about its axis at a predictable rate. d. the sun orbits a nearby star called alpha centauri.

A47.2 g block of copper whose temperature is 480 k is placed in an insulating box with a 91.8 g block of lead whose temperature is 200 k. (a) what is the equilibrium temperature of the two-block system? (b) what is the change in the internal energy of the two-block system between the initial state and the equilibrium state? (c) what is the change in the entropy of the two-block system? the heat capacities of copper and lead are 386 j/kg·k and 128 j/kg·k, respectively.