Answer:
Q = c M ÎT Â Â Â where c is the heat capacity and M the mass present
Q2 / Q1 = M2 / M1 Â Â since the other factors are the same
M = Ď V Â Â where Ď is the density
M = Ď Î (d / 2)^2 Â Â Â Â Â where d is the diameter of the sphere
M2 / M1 = (2 D/2)^2 / (D/2)^2 = 4
It will take 4Q heat to heat the second sphere