I believe I know the answer to #4
ANSWER: Two moles to a first approximation
*Disclaimer* I'm pretty sure I'm right, but I could be wrong
Yellow because Pangea all the continents were together
If I understand this right, the two elements are Nickel and Copper, elements 28 and 28, respectively. A nickel is worth 5 cents, and a penny, originally comprised of copper, is worth one - the total being six cents.
You are correct, but you needn't worry about the signs so much. Just remember that the negative sign is used to denote a loss of energy; since the water is hotter, it will be losing energy (-Q) and the iron will gain energy (Q). Now, we substitute the values:
-149.3 * 4.184 * (T - 95) = 412 * 0.44 * (T - 5)
Solving this equation for T,
T = 74.8 °C
In general, the diffusion coefficient is inversely proportional to pressure. This is also an observed fact: gas production rates from coal seams tend to increase as the reservoir pressure goes down.
