Iron
m = 20 grams
c = 0.412 J/(g oK)
t = 10oK
Heat = m * c * delta T
Heat = 20 * 0.412 * 10
Heat = 83.8 Joules.
Gold
The gold uses the same formula
m = 15 grams
c = 0.129
delta t = 15 oK
Heat = 15 * 0.129 * 15
Heat = 29.0 J
The iron requires more heat. (energy) <<< answer